Great news everyone. Itchboy was able to isolate the mod's performance issues to the Civil Car Pack, as well as a few other smaller things. This means the lag everyone was experiencing has more or less been fixed!
I will be taking over development for a while and getting things looking pretty and filling in some gaps here and there. We will then move forward with a beta, and eventually a release. The biggest hurdle has been cleared.
This new build was tested, and performed well, on a computer with a Pentium dual-core processor and integrated nVidia graphics chip. So all those with lower-end PCs, to an extent, should be able to run the next release of the mod smoothly.