Minecraft is RIDICULOUSLY gpu intensive. It really takes very little out of the CPU under normal circumstances (Unless an admin spawns 300 bats in a closed room that you are in) I think your CPU is just fine.
You are completely wrong, I suggest you do your research properly.
Minecraft barely uses any GPU at all, it is extremely CPU intensive, but limited to only one core. If you have a shitty i7 or something, you could misstake it for not using CPU because it will show as 13% CPU usage, while infact your CPU is what is slowing it down.
@mike88931 The HD 5450 is terrible, and should not at all be used with your resolution.