Need help with glFinish performance

I'm having a little trouble finding a performance problem. Typically I get around 90-100 FPS on my machine, but now and then I will start the game and it will run at 20-25 fps. I've done some profiling during these slow times and found that glFinish is over 80% of the execution time.

Here is an excerpt:

Profiler Data Dump:
Ordered by non-sub total time -
%%NSTime  %% Time  Invoke #  Name
 87.930  87.930       80 glFinish
  3.772   4.070       80 T2D_t2dSceneWindow_onRender
  1.956   6.026       80 CanvasRenderControls
  1.257   3.349       80 ClientProcess
  0.657   1.083    37809 T2D_t2dSceneObject_updateLocalPhysics
  0.448   0.476       80 ProcessMessages_MAIN
  0.309   0.468   114328 T2D_t2dSceneObject_updateSpatialConfig
  0.278   0.278    26878 T2D_t2dSceneObject_updateWorldClip



Ordered by non-sub total time -
%%NSTime  %% Time  Invoke #  Name
 37.478 -62.522        0 ROOT
100.000   0.006       80   MainLoop
 99.384   0.099       80     GameProcessEvents
 99.267   0.038       80       ProcessTimeEvent
 95.618   0.010       80         RenderFrame
 87.930  87.930       80           glFinish
  6.026   1.956       80           CanvasRenderControls
  4.070   3.772       80             T2D_t2dSceneWindow_onRender
  0.195   0.195       80               t2dSceneContainer_findObjects
  0.064   0.064    30240               NewFontGetCharInfo

Any ideas?