Just to make sure this is clear: It works better with overlay enabled and worse with overlay disabled?
Closing as general video driver performance from 2013 is no longer relevant.
This is low end hardware and the desktop environment most likely was compositing a volume level indicator to cause the performance drop.
Nothing extracted yet.
When I use my FN keys during in-game without the Steam overlay, the FPS drops around 50%. Was running it on 1024x768.
On the other hand, when I changed the volume when I had the Steam overlay on, it did not impact the FPS in my opinion.
System Info:
Processor Information:
Vendor: AuthenticAMD
Speed: 1600 Mhz
2 logical processors
2 physical processors
HyperThreading: Unsupported
FCMOV: Supported
SSE2: Supported
SSE3: Supported
SSSE3: Supported
SSE4a: Supported
SSE41: Unsupported
SSE42: Unsupported
Network Information:
Network Speed:
Operating System Version:
Ubuntu 12.10 (64 bit)
Kernel Name: Linux
Kernel Version: 3.5.0-25-generic
X Server Vendor: The X.Org Foundation
X Server Release: 11300000
X Window Manager: Compiz
Steam Runtime Version: steam-runtime-release-i386_2013-02-22
Video Card:
Driver: ATI Technologies Inc. AMD Radeon HD 6310 Graphics
Sound card:
Audio device: ATI R6xx HDMI
Memory:
RAM: 3557 Mb
Miscellaneous:
UI Language: English
LANG: en_CA.UTF-8
Microphone: Not set
Total Hard Disk Space Available: 95714 Mb
Largest Free Hard Disk Block: 45982 Mb
Installed software:
Recent Failure Reports: