Heavy permenant performance degredation from trails

in a test mod I fire huge numbers of weapons with trails in a short period of time. Before this happens I have a solid 120 fps, afterwards in an otherwise identical scene (all trails faded and weapons gone) I idle in the 17-20fps. A mission restart brings idle up to 20-25ish.

this seems to be tied entirely to trails. If I turn trails off I don't see this, toggling other features such as weapon lighting doesn't have an impact.

Profiling shows that the vast majority of frametime in the slow period is spent in `gropengltnl.cpp:gr_opengl_update_buffer_data()`

Attached is a test mod, launch it with fps display on and run the included mission, and you'll see the behavior in moments.
[trailthrash.zip](https://github.com/scp-fs2open/fs2open.github.com/files/10419375/trailthrash.zip)