Hello Joel, Thursday, December 15, 2005, 2:42:03 PM, you wrote: JR> Here's the latest and greatest version put together with Einar's help. let's analyze execution of this thread. it has 2000-6000 events in his Map with an expiration time in the range 0-60 sec. it sleeps half a second, then wakes and finds/deletes minimal values from map until all events which are within this half-a-second will be performed and then sleeps again if half-second precision of performing events is appropriate for you, why don't use solution which holds all events for given second in one list? you can use array of such lists, or map of lists, or even ordered list of lists - it will contain only 60 elements at any time the most advanced solution will be array used as round buffer, whose size==maximal event timing i still don't understand why timings of your events may be different. you always say us that in each run timing is constant - 9 min, 1 min -- Best regards, Bulat mailto:bulatz@HotPOP.com