sluggish window dragging on r600

[Matthew Monaco]

I have a desktop with an integrated Radeon HD 4200 (RS880), AMD Phenom II X4 
965. Driver v6.14.2
I also have a laptop with an i915, Intel Core i3 M370. Driver v2.16.0

Both are on linux 3.0.4. Both are running gnome 3 in fallback mode. Both have 
identical 1920x1080 monitors connected through HDMI ports (The laptop's LVDS is 
disabled).

Presumably the desktop is a stronger system with a faster CPU and comparable GPU 
(don't know much about the differences).

When I drag a window via the title bar on the laptop, everything is smooth; the 
window stays with the mouse cursor.

When I drag a window via the title bar on the desktop, it's sluggish; the window 
lags behind the cursor.

Is it likely that something is configured incorrectly, or is there something 
implemented in the intel driver that is missing from radeon?



Desktop xorg.conf ==========================================================
Section "Device"
	Identifier   "rs880_radeonhd4200"
	Driver       "radeon"

	Option       "Monitor-HDMI-0" "hdmi"
	Option       "Monitor-VGA-0"  "vga"

	#Option       "ColorTiling" "on"
	#Option       "EnablePageFlip" "on"
EndSection

Section "Monitor"
	Identifier   "hdmi"
EndSection

Section "Monitor"
	Identifier   "vga"
	Option       "Enable" "false"
EndSection

Laptop  xorg.conf ==========================================================
Section "Device"
	Identifier "i915"
	Driver     "intel"
	
	Option     "monitor-LVDS1"  "lvds"
	Option     "monitor-HDMI1"  "hdmi"
	Option     "monitor-VGA1"   "vga"
	Option     "monitor-DP1"    "dp"
EndSection

Section "Monitor"
	Identifier "lvds"
EndSection

Section "Monitor"
	Identifier "hdmi"
EndSection

Section "Monitor"
	Identifier "vga"
	Option     "Enable" "false"
EndSection

Section "Monitor"
	Identifier "dp"
	Option     "Ignore" "true"
EndSection