Many hardware and software related issues could cause a slow rendering performance in Modelo. Here are some suggestions to test:
1. Update graphic card drive
2. Update Chrome to latest version
3. Chrome: settings>advanced settings> turn on hardware acceleration (or turn it off)
4. Try Safari to check if it is faster than in Chrome
5. laptop to be plugged into power (GPU goes to a power saving mode when on battery)
If it is still slow after doing the items above, it could be caused by the model itself. This article talks about how to optimize your SketchUp file.