Base install of Jaunty with Compiz enabled had lots of lag/sluggishness. The mtrr fix (see first post) + adding below lines to /etc/X11/xorg.conf has improved the performance a lot:
00:00.0 Host bridge: Intel Corporation Mobile 945GM/PM/GMS, 943/940GML and 945GT Express Memory Controller Hub (rev 03)
00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03)
I removed the tiling option since it caused slowness. No kernel changes or downgrading of Intel drivers was done. Hope this is useful to anyone with similar graphics.
Identifier "Configured Video Device"
Option "EXAOptimizeMigration" "true"
Option "MigrationHeuristic" "greedy"