I already have optifine and did the lowest setting. I got a 4x4 texture pack and a 1x1 texture pack (I use th 4x4 when minecraft isn't lagging). I can start up my laptop, around 100 fps. Then after 5 minutes it drops to 20, then 1. It's really annoying cause i can't play servers properly. No, i don't have anything running in the background. Here are my pc specs.
System:
Microsoft Window XP (Downgraded from Vista)
Professional
Version 2002
Service Pack 3
Computer:
Intel(R) Core(TM)2 Duo CPU
T5250 @ 1.50GHz
1.50GHz, 1.99GB of RAM
System:
Microsoft Window XP (Downgraded from Vista)
Professional
Version 2002
Service Pack 3
Computer:
Intel(R) Core(TM)2 Duo CPU
T5250 @ 1.50GHz
1.50GHz, 1.99GB of RAM
Bit: 32
Laptop: Acer Aspire 5720