I don't know why. It's happening after I install Ubuntu. (1-2 days later)
I'm using Chrome (64-bit - last version) and Pidgin at the same time. It's just that. First opening is normal but when I use Chrome for a while, ubuntu is slowing down. (I have 1 active extension for Chrome, it's for new tab) But everything is okay when I use Chrome with Microsoft Windows.
Maybe my system isn't good. But my graphic card is really bad because I'm using onboard. (Foxconn g41mxe motherboard, Intel g41)
Ram: 2 GB
CPU: Pentium(R) Dual-Core CPU E5400 @ 2.70GHz × 2
Graphic: Intel g41,
OS Type: 64-bit
Disk: 201 GB (for home directory, I'm using 50 GB for root directory)
Swap size: 4096 MB
HDD: 1 TB, new
*I've installed zram also*