Unity Dash is unbearably slow after upgrade (13.10 32-bit)

I recently upgraded a 12.04 LTS Wubi installation to 13.10. The Unity Dash is nearly impossible to use on 13.10 due to the immense amount of lag it produces when opening, taking about 8 seconds to open, frame by frame. Typing is recognized at an average of two letters per second. On top of that the top area of the screen is flashing with slightly slanted yellow and black lines (lack of a better description) while it is open.

I am used a modified Dell Latitude D610, with 1GB of RAM and an (as recognized by Windows) ATI Radeon Mobility X300 graphics card. Output from /usr/lib/nux/unity_support_test -p says Unity 3D is supposed to run fine:

OpenGL vendor string:   X.Org R300 Project
OpenGL renderer string: Gallium 0.4 on ATI RV370
OpenGL version string:  2.1 Mesa 9.2.1

Not software rendered:    yes
Not blacklisted:          yes
GLX fbconfig:             yes

GLX texture from pixmap:  yes
GL npot or rect textures: yes
GL vertex program:        yes
GL fragment program:      yes
GL vertex buffer object:  yes
GL framebuffer object:    yes
GL version is 1.4+:       yes

Unity 3D supported:       yes

Something obviously changed in the way Unity renders the Dash. Is there a way to revert to the old rendering? Upgrade to a different driver? I don't know.