Why is my CPU usage so high playing minecraft?

when i run Minecraft my CPU usage bumps up from 10 to
50-60% it used to only be at 20-35% and now javaw.exe *32
Memory(private working set) is at a high 295,00k+ at times, it used to be 110,000k-150,000k

I also just cleaned my CPU to see if it made any difference, but nothing has changed(i do not know if it would help or not but i did it anyway)

I just want to know if this is normal, if not please help D:

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