[ubuntu] install 12.04 on laptop HP ProBook 4540s

I am having difficulty installing Ubuntu 12.04 64-bit.
after installing all the interfaces is very slow, even though the CPU load of about max 36%

hp probook 4540s
Intel Core i7 3632QM with Intel HM76 Express
DDR3 12Gb
AMD Radeon HD 7650M + Intel HD Graphics 4000