diff --git a/chrome/content/zotero/xpcom/data/collection.js b/chrome/content/zotero/xpcom/data/collection.js
index 962d7a7cb..3aae995f7 100644
--- a/chrome/content/zotero/xpcom/data/collection.js
+++ b/chrome/content/zotero/xpcom/data/collection.js
@@ -259,7 +259,7 @@ Zotero.Collection.prototype._saveData = Zotero.Promise.coroutine(function* (env)
 	var isNew = env.isNew;
 	var options = env.options;
 
-	var collectionID = env.id = this._id = this.id ? this.id : yield Zotero.ID.get('collections');
+	var collectionID = this._id = this.id ? this.id : Zotero.ID.get('collections');
 	
 	Zotero.debug("Saving collection " + this.id);
 	
@@ -279,10 +279,7 @@ Zotero.Collection.prototype._saveData = Zotero.Promise.coroutine(function* (env)
 		let placeholders = env.sqlColumns.map(function () '?').join();
 		let sql = "INSERT INTO collections (" + env.sqlColumns.join(', ') + ") "
 			+ "VALUES (" + placeholders + ")";
-		var insertID = yield Zotero.DB.queryAsync(sql, env.sqlValues);
-		if (!collectionID) {
-			collectionID = env.id = insertID;
-		}
+		yield Zotero.DB.queryAsync(sql, env.sqlValues);
 	}
 	else {
 		let sql = 'UPDATE collections SET '
diff --git a/chrome/content/zotero/xpcom/data/creators.js b/chrome/content/zotero/xpcom/data/creators.js
index 177596a89..94fbeaae8 100644
--- a/chrome/content/zotero/xpcom/data/creators.js
+++ b/chrome/content/zotero/xpcom/data/creators.js
@@ -90,7 +90,7 @@ Zotero.Creators = new function() {
 			sql, [data.firstName, data.lastName, data.fieldMode]
 		);
 		if (!id && create) {
-			id = yield Zotero.ID.get('creators');
+			id = Zotero.ID.get('creators');
 			let sql = "INSERT INTO creators (creatorID, firstName, lastName, fieldMode) "
 				+ "VALUES (?, ?, ?, ?)";
 			yield Zotero.DB.queryAsync(
diff --git a/chrome/content/zotero/xpcom/data/dataObject.js b/chrome/content/zotero/xpcom/data/dataObject.js
index 9c6628811..19ce3f9c8 100644
--- a/chrome/content/zotero/xpcom/data/dataObject.js
+++ b/chrome/content/zotero/xpcom/data/dataObject.js
@@ -902,7 +902,7 @@ Zotero.DataObject.prototype._initSave = Zotero.Promise.coroutine(function* (env)
 	
 	// Undo registerObject() on failure
 	var func = function () {
-		this.ObjectsClass.unload(env.id);
+		this.ObjectsClass.unload(this._id);
 	}.bind(this);
 	if (env.options.tx) {
 		env.transactionOptions.onRollback = func;
diff --git a/chrome/content/zotero/xpcom/data/feedItem.js b/chrome/content/zotero/xpcom/data/feedItem.js
index 068f87fb7..771c12560 100644
--- a/chrome/content/zotero/xpcom/data/feedItem.js
+++ b/chrome/content/zotero/xpcom/data/feedItem.js
@@ -153,7 +153,7 @@ Zotero.FeedItem.prototype._initSave = Zotero.Promise.coroutine(function* (env) {
 		var superOnCommit = env.transactionOptions.onCommit;
 		env.transactionOptions.onCommit = () => {
 			if (superOnCommit) superOnCommit();
-			this.ObjectsClass._setGUIDMapping(this.guid, env.id);
+			this.ObjectsClass._setGUIDMapping(this.guid, this._id);
 		};
 	}
 	
@@ -165,7 +165,15 @@ Zotero.FeedItem.prototype._saveData = Zotero.Promise.coroutine(function* (env) {
 	
 	if (this._changed.feedItemData || env.isNew) {
 		var sql = "REPLACE INTO feedItems VALUES (?,?,?,?)";
-		yield Zotero.DB.queryAsync(sql, [env.id, this.guid, this._feedItemReadTime, this._feedItemTranslatedTime]);
+		yield Zotero.DB.queryAsync(
+			sql,
+			[
+				this.id,
+				this.guid,
+				this._feedItemReadTime,
+				this._feedItemTranslatedTime
+			]
+		);
 		
 		this._clearChanged('feedItemData');
 	}
diff --git a/chrome/content/zotero/xpcom/data/item.js b/chrome/content/zotero/xpcom/data/item.js
index 9216d90e8..a15503655 100644
--- a/chrome/content/zotero/xpcom/data/item.js
+++ b/chrome/content/zotero/xpcom/data/item.js
@@ -1225,7 +1225,7 @@ Zotero.Item.prototype._saveData = Zotero.Promise.coroutine(function* (env) {
 	// Primary fields
 	//
 	// If available id value, use it -- otherwise we'll use autoincrement
-	var itemID = env.id = this._id = this.id ? this.id : yield Zotero.ID.get('items');
+	var itemID = this._id = this.id ? this.id : Zotero.ID.get('items');
 	
 	env.sqlColumns.push(
 		'itemTypeID',
@@ -1259,10 +1259,7 @@ Zotero.Item.prototype._saveData = Zotero.Promise.coroutine(function* (env) {
 		
 		let sql = "INSERT INTO items (" + env.sqlColumns.join(", ") + ") "
 			+ "VALUES (" + env.sqlValues.map(function () "?").join() + ")";
-		var insertID = yield Zotero.DB.queryAsync(sql, env.sqlValues);
-		if (!itemID) {
-			itemID = env.id = insertID;
-		}
+		yield Zotero.DB.queryAsync(sql, env.sqlValues);
 		
 		if (!env.options.skipNotifier) {
 			Zotero.Notifier.queue('add', 'item', itemID, env.notifierData);
@@ -1305,7 +1302,7 @@ Zotero.Item.prototype._saveData = Zotero.Promise.coroutine(function* (env) {
 			
 			let valueID = yield Zotero.DB.valueQueryAsync(valueSQL, [value], { debug: true })
 			if (!valueID) {
-				valueID = yield Zotero.ID.get('itemDataValues');
+				valueID = Zotero.ID.get('itemDataValues');
 				yield Zotero.DB.queryAsync(insertValueSQL, [valueID, value], { debug: false });
 			}
 			
diff --git a/chrome/content/zotero/xpcom/data/library.js b/chrome/content/zotero/xpcom/data/library.js
index 10f618cc6..09d00d485 100644
--- a/chrome/content/zotero/xpcom/data/library.js
+++ b/chrome/content/zotero/xpcom/data/library.js
@@ -444,7 +444,7 @@ Zotero.Library.prototype._saveData = Zotero.Promise.coroutine(function* (env) {
 	}
 	
 	if (env.isNew) {
-		let id = yield Zotero.ID.get('libraries'); // Cannot retrieve auto-incremented ID with async queries
+		let id = Zotero.ID.get('libraries');
 		changedCols.unshift('libraryID');
 		params.unshift(id);
 		
diff --git a/chrome/content/zotero/xpcom/data/tags.js b/chrome/content/zotero/xpcom/data/tags.js
index 18a141816..450e751ee 100644
--- a/chrome/content/zotero/xpcom/data/tags.js
+++ b/chrome/content/zotero/xpcom/data/tags.js
@@ -65,12 +65,9 @@ Zotero.Tags = new function() {
 		var sql = "SELECT tagID FROM tags WHERE name=?";
 		var id = yield Zotero.DB.valueQueryAsync(sql, data.tag);
 		if (!id && create) {
-			id = yield Zotero.ID.get('tags');
+			id = Zotero.ID.get('tags');
 			let sql = "INSERT INTO tags (tagID, name) VALUES (?, ?)";
-			let insertID = yield Zotero.DB.queryAsync(sql, [id, data.tag]);
-			if (!id) {
-				id = insertID;
-			}
+			yield Zotero.DB.queryAsync(sql, [id, data.tag]);
 		}
 		return id;
 	});
diff --git a/chrome/content/zotero/xpcom/id.js b/chrome/content/zotero/xpcom/id.js
index 0c9d5d50b..b8c369768 100644
--- a/chrome/content/zotero/xpcom/id.js
+++ b/chrome/content/zotero/xpcom/id.js
@@ -1,9 +1,9 @@
 /*
     ***** BEGIN LICENSE BLOCK *****
     
-    Copyright © 2009 Center for History and New Media
+    Copyright © 2016 Center for History and New Media
                      George Mason University, Fairfax, Virginia, USA
-                     http://zotero.org
+                     https://www.zotero.org
     
     This file is part of Zotero.
     
@@ -24,310 +24,38 @@
 */
 
 Zotero.ID_Tracker = function () {
-	this.getBigInt = getBigInt;
-	this.skip = skip;
-	this.getTableName = getTableName;
-	
-	// Number of ids to compare against at a time
-	this.__defineGetter__('numIDs', function () 10000);
-	
-	// Number of times to try increasing the maxID if first range fails
-	this.__defineGetter__('maxTries', function () 3);
-	
-	// Total number of ids to find
-	this.__defineGetter__('maxToFind', function () 1000);
-	
-	var _available = {};
-	var _min = {};
-	var _skip = {};
+	var _tables = [
+		'collections',
+		'creators',
+		'customFields',
+		'customItemTypes',
+		'itemDataValues',
+		'items',
+		'libraries',
+		'proxies',
+		'savedSearches',
+		'tags'
+	];
+	var _nextIDs = {};
 	
 	
-	/*
-	 * Gets an unused primary key id for a DB table
-	 */
-	this.get = Zotero.Promise.coroutine(function* (table, notNull) {
-		table = this.getTableName(table);
-		
-		switch (table) {
-			// Autoincrement tables
-			//
-			// Callers need to handle a potential NULL for these unless they
-			// pass |notNull|
-			case 'libraries':
-			case 'items':
-			case 'creators':
-			case 'creatorData':
-			case 'collections':
-			case 'savedSearches':
-			case 'tags':
-			case 'customItemTypes':
-			case 'customFields':
-				var id = yield _getNextAvailable(table);
-				if (!id && notNull) {
-					return _getNext(table);
-				}
-				return id;
-			
-			// Non-autoincrement tables
-			//
-			// TODO: Use for everything
-			case 'itemDataValues':
-			case 'proxies':
-				var id = yield _getNextAvailable(table);
-				if (!id) {
-					// If we can't find an empty id quickly, just use MAX() + 1
-					return _getNext(table);
-				}
-				return id;
-			
-			default:
-				throw ("Unsupported table '" + table + "' in Zotero.ID.get()");
+	this.init = Zotero.Promise.coroutine(function* () {
+		for (let table of _tables) {
+			_nextIDs[table] = yield _getNext(table);
 		}
 	});
 	
-	function getBigInt(max) {
-		if (!max) {
-			max = 9007199254740991;
-		}
-		return Math.floor(Math.random() * (max)) + 1;
-	}
-	
 	
 	/**
-	 * Mark ids as used
-	 *
-	 * @param	string		table
-	 * @param	int|array	ids			Item ids to skip
+	 * Gets an unused primary key id for a DB table
 	 */
-	function skip(table, ids) {
-		table = this.getTableName(table);
-		
-		switch (ids.constructor.name) {
-			case 'Array':
-				break;
-				
-			case 'Number':
-				ids = [ids];
-				break;
-				
-			default:
-				throw ("ids must be an int or array of ints in Zotero.ID.skip()");
+	this.get = function (table) {
+		if (!_nextIDs[table]) {
+			throw new Error("IDs not loaded for table '" + table + "'");
 		}
 		
-		if (!ids.length) {
-			return;
-		}
-		
-		if (!_skip[table]) {
-			_skip[table] = {};
-		}
-		
-		for (var i=0, len=ids.length; i<len; i++) {
-			_skip[table][ids[i]] = true;
-		}
-	}
-	
-	
-	function getTableName(table) {
-		// Used in sync.js
-		if (table == 'searches') {
-			table = 'savedSearches';
-		}
-		
-		switch (table) {
-			case 'collections':
-			case 'creators':
-			case 'creatorData':
-			case 'itemDataValues':
-			case 'items':
-			case 'libraries':
-			case 'savedSearches':
-			case 'tags':
-			case 'customItemTypes':
-			case 'customFields':
-			case 'proxies':
-				return table;
-				
-			default:
-				throw ("Invalid table '" + table + "' in Zotero.ID");
-		}
-	}
-	
-	
-	/*
-	 * Returns the lowest available unused primary key id for table,
-	 * or NULL if none could be loaded in _loadAvailable()
-	 */
-	var _getNextAvailable = Zotero.Promise.coroutine(function* (table) {
-		if (!_available[table]) {
-			yield _loadAvailable(table);
-		}
-		
-		var arr = _available[table];
-		
-		while (arr[0]) {
-			var id = arr[0][0];
-			
-			// End of range -- remove range
-			if (id == arr[0][1]) {
-				arr.shift();
-				
-				// Prepare table for refresh if all rows used
-				if (arr.length == 0) {
-					delete _available[table];
-				}
-			}
-			// Within range -- increment
-			else {
-				arr[0][0]++;
-			}
-			
-			if (_skip[table] && _skip[table][id]) {
-				Zotero.debug("Skipping " + table + " id " + id);
-				if (!_available[table]) {
-					yield _loadAvailable(table);
-				}
-				continue;
-			}
-			
-			_min[table] = id;
-			return id;
-		}
-		return null;
-	});
-	
-	
-	/*
-	 * Get MAX(id) + 1 from table
-	 */
-	var _getNext = Zotero.Promise.coroutine(function* (table) {
-		var column = _getTableColumn(table);
-		
-		var sql = 'SELECT MAX(';
-		if (_skip[table]) {
-			var max = 0;
-			for (var id in _skip[table]) {
-				if (parseInt(id) > max) {
-					max = parseInt(id);
-				}
-			}
-			if (!max) {
-				throw new Error("_skip['" + table + "'] must contain positive values");
-			}
-			sql += 'MAX(' + column + ', ' + max + ')';
-		}
-		else {
-			sql += column;
-		}
-		sql += ')+1 FROM ' + table;
-		return Zotero.DB.valueQueryAsync(sql);
-	});
-	
-	
-	/*
-	 * Loads available ids for table into memory
-	 */
-	var _loadAvailable = Zotero.Promise.coroutine(function* (table) {
-		Zotero.debug("Loading available ids for table '" + table + "'");
-		
-		var minID = _min[table] ? _min[table] + 1 : 1;
-		var numIDs = Zotero.ID.numIDs; 
-		var maxTries = Zotero.ID.maxTries; 
-		var maxToFind = Zotero.ID.maxToFind;
-		
-		var column = _getTableColumn(table);
-		
-		switch (table) {
-			case 'creators':
-			case 'creatorData':
-			case 'items':
-			case 'itemDataValues':
-			case 'tags':
-				break;
-			
-			case 'libraries':
-			case 'collections':
-			case 'savedSearches':
-			case 'customItemTypes':
-			case 'customFields':
-			case 'proxies':
-				var maxToFind = 100;
-				break;
-			
-			default:
-				throw ("Unsupported table '" + table + "' in Zotero.ID._loadAvailable()");
-		}
-		
-		var maxID = minID + numIDs - 1;
-		var sql = "SELECT " + column + " FROM " + table
-			+ " WHERE " + column + " BETWEEN ? AND ? ORDER BY " + column;
-		var ids = yield Zotero.DB.columnQueryAsync(sql, [minID, maxID]);
-		// If no ids found, we have numIDs unused ids
-		if (!ids) {
-			maxID = Math.min(maxID, minID + (maxToFind - 1));
-			Zotero.debug("Found " + (maxID - minID + 1) + " available ids in table '" + table + "'");
-			_available[table] = [[minID, maxID]];
-			return;
-		}
-		
-		// If we didn't find any unused ids, try increasing maxID a few times
-		while (ids.length == numIDs && maxTries>0) {
-			Zotero.debug('No available ids found between ' + minID + ' and ' + maxID + '; trying next ' + numIDs);
-			minID = maxID + 1;
-			maxID = minID + numIDs - 1;
-			ids = yield Zotero.DB.columnQueryAsync(sql, [minID, maxID]);
-			maxTries--;
-		}
-		
-		// Didn't find any unused ids -- _getNextAvailable() will return NULL for
-		// this table for rest of session
-		if (ids.length == numIDs) {
-			Zotero.debug("Found no available ids in table '" + table + "'");
-			_available[table] = [];
-			return;
-		}
-		
-		var available = [], found = 0, j = 0, availableStart = null;
-		
-		for (var i=minID; i<=maxID && found<maxToFind; i++) {
-			// We've gone past the found ids, so all remaining ids up to maxID
-			// are available
-			if (!ids[j]) {
-				available.push([i, maxID]);
-				found += (maxID - i) + 1;
-				break;
-			}
-			
-			// Skip ahead while ids are occupied
-			if (ids[j] == i) {
-				j++;
-				continue;
-			}
-			
-			// Advance counter while it's below the next used id
-			while (ids[j] > i && i<=maxID) {
-				if (!availableStart) {
-					availableStart = i;
-				}
-				i++;
-				
-				if ((found + (i - availableStart) + 1) > maxToFind) {
-					break;
-				}
-			}
-			if (availableStart) {
-				available.push([availableStart, i-1]);
-				// Keep track of how many empties we've found
-				found += ((i-1) - availableStart) + 1;
-				availableStart = null;
-			}
-			j++;
-		}
-		
-		Zotero.debug("Found " + found + " available ids in table '" + table + "'");
-		
-		_available[table] = available;
-	});
+		return ++_nextIDs[table];
+	};
 	
 	
 	function _getTableColumn(table) {
@@ -351,33 +79,17 @@ Zotero.ID_Tracker = function () {
 				return table.substr(0, table.length - 1) + 'ID';
 		}
 	}
+	
+	
+	/**
+	 * Get MAX(id) + 1 from table
+	 *
+	 * @return {Promise<Integer>}
+	 */
+	function _getNext(table) {
+		var sql = 'SELECT COALESCE(MAX(' + _getTableColumn(table) + ') + 1, 1) FROM ' + table;
+		return Zotero.DB.valueQueryAsync(sql);
+	};
 }
 
 Zotero.ID = new Zotero.ID_Tracker;
-
-/**
- * Notifier observer to mark saved object ids as used
- */
-Zotero.ID.EventListener = new function () {
-	this.init = init;
-	this.notify = notify;
-	
-	function init() {
-		Zotero.Notifier.registerObserver(this);
-	}
-	
-	
-	function notify(event, type, ids) {
-		if (event == 'add') {
-			try {
-				var table = Zotero.ID.getTableName(type);
-			}
-			// Skip if not a table we handle
-			catch (e) {
-				return;
-			}
-			Zotero.ID.skip(table, ids);
-		}
-	}
-}
-
diff --git a/chrome/content/zotero/xpcom/proxy.js b/chrome/content/zotero/xpcom/proxy.js
index a80fd413b..90d0c86f4 100644
--- a/chrome/content/zotero/xpcom/proxy.js
+++ b/chrome/content/zotero/xpcom/proxy.js
@@ -645,7 +645,7 @@ Zotero.Proxy.prototype.save = Zotero.Promise.coroutine(function* (transparent) {
 				);
 				yield Zotero.DB.queryAsync("DELETE FROM proxyHosts WHERE proxyID = ?", [this.proxyID]);
 			} else {
-				let id = yield Zotero.ID.get('proxies');
+				let id = Zotero.ID.get('proxies');
 				yield Zotero.DB.queryAsync(
 					"INSERT INTO proxies (proxyID, multiHost, autoAssociate, scheme) VALUES (?, ?, ?, ?)",
 					[id, this.multiHost ? 1 : 0, this.autoAssociate ? 1 : 0, this.scheme]
diff --git a/chrome/content/zotero/xpcom/search.js b/chrome/content/zotero/xpcom/search.js
index 805d812d8..9fc9695d3 100644
--- a/chrome/content/zotero/xpcom/search.js
+++ b/chrome/content/zotero/xpcom/search.js
@@ -148,7 +148,7 @@ Zotero.Search.prototype._saveData = Zotero.Promise.coroutine(function* (env) {
 	var isNew = env.isNew;
 	var options = env.options;
 	
-	var searchID = env.id = this._id = this.id ? this.id : yield Zotero.ID.get('savedSearches');
+	var searchID = this._id = this.id ? this.id : Zotero.ID.get('savedSearches');
 	
 	env.sqlColumns.push(
 		'savedSearchName'
@@ -164,10 +164,7 @@ Zotero.Search.prototype._saveData = Zotero.Promise.coroutine(function* (env) {
 		let placeholders = env.sqlColumns.map(function () '?').join();
 		let sql = "INSERT INTO savedSearches (" + env.sqlColumns.join(', ') + ") "
 			+ "VALUES (" + placeholders + ")";
-		var insertID = yield Zotero.DB.queryAsync(sql, env.sqlValues);
-		if (!searchID) {
-			searchID = env.id = insertID;
-		}
+		yield Zotero.DB.queryAsync(sql, env.sqlValues);
 	}
 	else {
 		let sql = 'UPDATE savedSearches SET '
diff --git a/chrome/content/zotero/xpcom/zotero.js b/chrome/content/zotero/xpcom/zotero.js
index 06adf1e4c..0964c1d22 100644
--- a/chrome/content/zotero/xpcom/zotero.js
+++ b/chrome/content/zotero/xpcom/zotero.js
@@ -621,6 +621,7 @@ Components.utils.import("resource://gre/modules/osfile.jsm");
 				// Initialize Locate Manager
 				Zotero.LocateManager.init();
 				
+				yield Zotero.ID.init();
 				yield Zotero.Collections.init();
 				yield Zotero.Items.init();
 				yield Zotero.Searches.init();