This is a copy of a FAQ I just posted:

Calling DoEvents() has always been horribly slow in VFP. While reporting another issue with Hong-Chee Tan at Microsoft he found that moving the mouse around alters the test code I sent him. So this fact gives a workaround to speed DoEvents back up using a MOUSE command. Try this code for example:

* doevtest.prg
lparameter llMouse

local x, i

x = seconds()

for i = 1 to 100
   if ( llMouse )
      mouse at mrow(), mcol()
   endif
   doevents()
endfor

activate window "debug output"
debugout seconds() - x

Run it with and without a .t. argument and see the difference in execution times 26 vs 0.5 seconds on a P2-300 Win95 class machine.