Usually I have ~70 fps, but when choosing another class it drops to 15-20.
Steps to reproduce:

• open class choosing window (fps drops to 15-20 and restores back to normal in a second or two)
• move mouse over class icons, every time you highlight another class fps drops to 15-20 and restores back to normal in a second or two.

Processor Information:
    Vendor:  AuthenticAMD
    Speed: 3000 Mhz
    4 logical processors
    4 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:  3.5.0-21-generic
    X Server vendor:  The X.Org Foundation
    X Server release:  11300000
    
Video Card:
    Driver:  ATI Technologies Inc. AMD Radeon HD 6800 Series    

    Driver Version:  4.2.11995 Compatibility Profile Context
    Desktop Color Depth: 24 bits per pixel
    Monitor Refresh Rate: 59 Hz
    VendorID:  0x1002
    DeviceID:  0x6739
    Number of Monitors:  1
    Number of Logical Video Cards:  1
    Primary Display Resolution:  1680 x 1050
    Desktop Resolution: 1680 x 1050
    Primary Display Size: 18,66" x 11,65"  (21,97" diag)
                                            47,4cm x 29,6cm  (55,8cm diag)
    Primary VRAM Not Detected
    
Sound card:
    Audio device: SigmaTel STAC9758,59
    
Memory:
    RAM:  7986 Mb
    
Miscellaneous:
    UI Language:  English
    LANG:  ru_RU.UTF-8
    Microphone:  Not set
    Total Hard Disk Space Available:  151644 Mb
    Largest Free Hard Disk Block:  13010 Mb
    
Installed software:
    
Recent Failure Reports:
    

Video drivers: AMD Catalyst 12.11 Beta11 x64