diff --git a/chrome/content/zotero/xpcom/data/creator.js b/chrome/content/zotero/xpcom/data/creator.js
index cea69f6b6a..c869d64f1b 100644
--- a/chrome/content/zotero/xpcom/data/creator.js
+++ b/chrome/content/zotero/xpcom/data/creator.js
@@ -536,7 +536,7 @@ Zotero.Creator.prototype._checkValue = function (field, value) {
 			break;
 			
 		case 'key':
-			if (!Zotero.ID.isValidKey(value)) {
+			if (!this._isValidKey(value)) {
 				this._invalidValueError(field, value);
 			}
 			break;
@@ -559,3 +559,8 @@ Zotero.Creator.prototype._generateKey = function () {
 Zotero.Creator.prototype._invalidValueError = function (field, value) {
 	throw ("Invalid '" + field + "' value '" + value + "' in Zotero.Creator._invalidValueError()");
 }
+
+Zotero.Creator.prototype._isValidKey = function (value) {
+	var re = /^[23456789ABCDEFGHIJKLMNPQRSTUVWXYZ]{8}$/
+	return re.test(value);
+}
diff --git a/chrome/content/zotero/xpcom/id.js b/chrome/content/zotero/xpcom/id.js
index 4d68d79111..731dc31c5e 100644
--- a/chrome/content/zotero/xpcom/id.js
+++ b/chrome/content/zotero/xpcom/id.js
@@ -24,342 +24,43 @@
 */
 
 Zotero.ID_Tracker = function () {
-	this.get = get;
-	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 _initialized = false;
+	var _tables = [
+		'collections',
+		'creators',
+		'creatorData',
+		'customFields',
+		'customItemTypes',
+		'itemDataValues',
+		'items',
+		'savedSearches',
+		'tags'
+	];
+	var _nextIDs = {};
 	
 	
-	/*
+	function _init() {
+		Zotero.debug("Initializing ids");
+		for (let table of _tables) {
+			_nextIDs[table] = _getNext(table);
+		}
+		_initialized = true;
+	}
+	
+	
+	/**
 	 * Gets an unused primary key id for a DB table
 	 */
-	function get(table, notNull) {
-		table = this.getTableName(table);
-		
-		switch (table) {
-			// Autoincrement tables
-			//
-			// Callers need to handle a potential NULL for these unless they
-			// pass |notNull|
-			case 'items':
-			case 'creators':
-			case 'creatorData':
-			case 'collections':
-			case 'savedSearches':
-			case 'tags':
-			case 'customItemTypes':
-			case 'customFields':
-				var id = _getNextAvailable(table);
-				if (!id && notNull) {
-					return _getNext(table);
-				}
-				return id;
-			
-			// Non-autoincrement tables
-			//
-			// TODO: use autoincrement instead where available in 1.5
-			case 'itemDataValues':
-				var id = _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.get = function (table) {
+		if (!_initialized) {
+			_init();
 		}
-	}
-	
-	
-	this.isValidKey = function (value) {
-		var re = /^[23456789ABCDEFGHIJKLMNPQRSTUVWXYZ]{8}$/
-		return re.test(value);
-	}
-	
-	
-	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
-	 */
-	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()");
+		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 'savedSearches':
-			case 'tags':
-			case 'customItemTypes':
-			case 'customFields':
-				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()
-	 */
-	function _getNextAvailable(table) {
-		if (!_available[table]) {
-			_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]) {
-					_loadAvailable(table);
-				}
-				continue;
-			}
-			
-			_min[table] = id;
-			return id;
-		}
-		return null;
-	}
-	
-	
-	/*
-	 * Get MAX(id) + 1 from table
-	 */
-	function _getNext(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 ("_skip['" + table + "'] must contain positive values in Zotero.ID._getNext()");
-			}
-			sql += 'MAX(' + column + ', ' + max + ')';
-		}
-		else {
-			sql += column;
-		}
-		sql += ')+1 FROM ' + table;
-		return Zotero.DB.valueQuery(sql);
-	}
-	
-	
-	/*
-	 * Loads available ids for table into memory
-	 */
-	function _loadAvailable(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 'collections':
-			case 'savedSearches':
-			case 'customItemTypes':
-			case 'customFields':
-				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 = Zotero.DB.columnQuery(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 = Zotero.DB.columnQuery(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;
-	}
-	
-	
-	/**
-	* Find a unique random id for use in a DB table
-	*
-	* (No longer used)
-	**/
-	function _getRandomID(table, max){
-		var column = _getTableColumn(table);
-		
-		var sql = 'SELECT COUNT(*) FROM ' + table + ' WHERE ' + column + '= ?';
-		
-		if (!max){
-			max = 16383;
-		}
-		
-		max--; // since we use ceil(), decrement max by 1
-		var tries = 3; // # of tries to find a unique id
-		for (var i=0; i<tries; i++) {
-			var rnd = Math.ceil(Math.random() * max);
-			var exists = Zotero.DB.valueQuery(sql, { int: rnd });
-			if (!exists) {
-				return rnd;
-			}
-		}
-		
-		// If no luck after number of tries, try a larger range
-		var sql = 'SELECT MAX(' + column + ') + 1 FROM ' + table;
-		return Zotero.valueQuery(sql);
-	}
+		return ++_nextIDs[table];
+	};
 	
 	
 	function _getTableColumn(table) {
@@ -377,33 +78,17 @@ 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.valueQuery(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);
-		}
-	}
-}
-