Yup your Ram is the problem consider adding AT LEAST another 512mb...here are some other tips to speed things up! Since you have such little Ram I HIGHLY RECOMMEND USING XUBUNTU!
- Change Swap
gksudo gedit /etc/sysctl.conf
ADD THIS ENTRY AT END AND SAVE
vm.swappiness=5
Remove bloatware
https://fixubuntu.com/
wget -q -O - https://fixubuntu.com/fixubuntu.sh | bash
Get the following Tweak Tools
Ubuntu Tweak ( sudo apt-get install ubuntu-tweak )
Tweak Tool ( sudo apt-get install gnome-tweak-tool )
Unity Tweak ( sudo apt-get install unity-tweak-tool )
Dconf Editor ( sudo apt-get install dconf-tools )
Compiz Config Editor ( sudo apt-get install compizconfig-settings-manager compiz-plugins-extra -y )
Review each section of each tool and modify as desired
Get Bleachbit
I suggest downloading the newest version as the one in the repository(Software Center) is old. You can download it here: http://bleachbit.sourceforge.net/download/linux
Review the following sites and modify your system as needed.
https://sites.google.com/site/easylinuxtipsproject/first#TOC-Decrease-the-swap-use-very-important-
https://sites.google.com/site/easylinuxtipsproject/speed
http://www.techsupportalert.com/content/best-free-software-linux.htm?page=0,0#Introduction
http://smashingweb.info/things-to-do-after-installing-ubuntu-14-04-lts-for-perfect-desktop/
http://ubuntuforums.org/showthread.php?t=140920
http://www.techsupportalert.com/content/tips-and-tricks-ubuntu-after-installation-ubuntu-1404.htm
Check FPS
Open terminal
type glxgears
hit enter
HOPE THIS INFO HELPS A BIT!
One other awesome tool I use is CPU Indicator
Open Terminal
Install
sudo apt-get install indicator-cpufreq
Run
'indicator-cpufreq' in terminal to launch
Reboot!!! You will see the icon in the top bar of unity interface.
Right or left click icon and select the fastest cpu speed or desired speed! This tool is AWESOME and will help a TON!