Uplink Runs Slow in Ubuntu

[Murderjetz]

I've been a long-time fan of Uplink and have played it many years ago on Windows. Now I run Ubuntu on my laptop and have discovered that Uplink is available for Ubuntu, so I purchased it. However I am finding that it is running a little slowly. There is about a one second delay after every button click. It is still playable, although not enjoyably so.
The strange thing is that, for about the first hour of play, it ran perfectly. It then suddenly started this button click delay. I've tried restarting the game, restarting my computer, turning music off, different screen resolutions... nothing seems to be fixing it.
I've found other posts which report similar problems but not on Ubuntu, and so I'm not sure how to translate the suggested solutions to Ubuntu. Any help would be appreciated, I really want to enjoy this game again!