[plt-scheme] MrEd app very slow on Ubuntu 9.10

Hi everybody,

One of my GUI apps was developed on OS X and now I've moved development
to Ubuntu 9.10 with Gnome. Everything works normally on OS X, but on
Ubuntu every window takes 10-30 secs to show up and user interface
elements like buttons have a delay of at least 5 secs until they
react---on a brand-new 2.6 GHz i7 machine with 6 GB RAM! For the record,
I've tried both the latest stable source release, which compiled fine,
and the older release in the Synaptic package manager. Memory limit
doesn't make a difference.

Other apps work fine and I haven't been able to produce a minimal
example. Does anyone have an idea where to look at and what might cause
this extreme delay. Are there some log-files I could check? Are there
some text% operations or window refresh routines that are drastically
slower on Ubuntu than on OS X?

Best,

Erich