Welcome to the forums.
Lots of people have had this problem, and I'm not sure of the reasons why, but these are the usual suggestions people give for this problem
Try turning all the in-game options to their lowest values, and see if that helps.
Also be aware that switching to other pages while in game will slow your timer, but the server timer continues at normal speed.
Running other programs at the same time can also slow your computer, and make this problem worse
Is it the latest version of supermechs you're playing (should say 'ver 2.5B in the bottom right of the loading screen)?
Have you tried playing it from the
official site?
--If none of that helps--
Is your computer relatively fast, browser and flash up to date etc.?
How is your
internet speed?
[check your speed against a server in Texas, as apparently that's where the Supermechs server is].