BT5 R3 Slow and laggy

I'm after some tips on where to start trying to find the cause of intermittent lag running BT5 R3 on a dell Latitude E6410. Its installed on the local HDD with a duel boot to windows 8, which is fine. I had the normal kernel panic with the Intel GPU but that was an easy fix after searching the forums but I'm not finding much on here for speed issues.

I've watched my processes for a while and can't see anything in there but it does seem like a process as it comes and goes, sometimes wicd will jump to the top around the same time but never taking all the system process. My main symptom is one minute I'm typing in the console, or any application and everything is fine then all of a sudden it'll lag and words are appearing a few seconds after being typed.

It does the same thing from a live CD version too. MD5 has been checked for consistency and that's fine.

Any pointers where to look are greatly appreciated.

Quick update. I've been looking into this further and have now found that xorg appears to be the CPU hog.

I've got the following errors in the Xorg.0.log but still not finding much to go on.

(WW) The directory "/usr/share/fonts/X11/cyrillic" does not exist.
(WW) The directory "/usr/share/fonts/X11/100dpi/" does not exist.
(WW) The directory "/usr/share/fonts/X11/75dpi/" does not exist.
(WW) The directory "/usr/share/fonts/X11/100dpi" does not exist.
(WW) The directory "/usr/share/fonts/X11/75dpi" does not exist.
(WW) Open ACPI failed (/var/run/acpid.socket) (No such file or directory)
(WW) Falling back to old probe method for vesa
(WW) Falling back to old probe method for fbdev

I'm wondering if the tweaks to grub to startx could be related. I'm running an Intel HD graphics card

For info I added the following to grub and then did a rebuild.

"quiet splash i915.modeset=1 vga=791"

What GUI are you using? Try switching from KDE/GNOME or vice versad

Well, if you are using intel open driver, yes, you must activate KMS as you did..You could have done it in the grub's edit mode or CLI mode before altering something, to see if it was going to work.

Anyway, the lines you posted "does not exist" is just a warning, not an error, and it shows issues on video resolution. Would you post the intel video model?...

Luck.