That suggest a CPU based bottleneck in your case. Toning that dial down will lead to smoother gameplay, and slightly more inaccurate transfers. You can also look for that mod that welds parts together, as it means less part-count, thus less physics calculation.
On the plus side, that also means your GPU can probably handle more than the stock KSP, so if you wanted to make it look prettier, most likely visual mods wont affect much of the performance.