FPS decrease after start...

Hi, in my arcade game when it start i have 200 fps, but after a time my fps decrease at 40-50 fps, Which can be the causes?JVM memory usage?My accelerated image become unaccelerated?
[189 byte] By [blowa] at [2007-10-3 3:46:41]
# 1

In game i create a lot of particle(im using fillRect method) but each particle have a life_time so when life_time is expired the particle is elimanted, and its image is flush and null (image.flush(); image=null).

My fps decrease when a lot of particle is on my screen, but dont increase when remove particle...

blowa at 2007-7-14 21:43:28 > top of Java-index,Other Topics,Java Game Development...
# 2
Now work becouse call System.gc() after 120 seconds, but when i call garbage collector i have a struct, its normal?
blowa at 2007-7-14 21:43:28 > top of Java-index,Other Topics,Java Game Development...