This update adds the following...
Optimised the missile guidance code so that guided missiles no longer cause a large drop in FPS when fired. In my testing guided missiles in flight now cost around 2-3 fps rather than about 30 previously! This has been something that's been bugging me for a while and I discovered I was doing multiple square root calculations which were not strictly necessary. The downside is the timer count down for Hellfire and Brimstone missiles now only updates every 0.5 seconds but this is something I can fix by doing a bit of interpolation between distance checks.
Added in some error checking code to the infantry system which I believe was causing a GPU crash very occasionally if the animation system tried to update a dead infantry unit just after it was removed from the game. Thanks to Sola20 for sending in a detailed report and player.log which pointed me in the right direction. I can't be 100% certain if this issue is fixed so if you encounter and crashes please let me know and send through you're player.log file and a short description of what was going on when it happened as best you can.