Render the timeline first by pressing enter.
Is this the workflow most people use while editing? It seems a bit cumbersome, as I would expect the software to be able to handle ~1 minute clips (any length really, but my test clip was short) with simple or complex effects w/o rendering. Just to be clear, my system is fully up-to-date, my graphics drivers are current, and most everything else seems copacetic. Cheers
To know whether your system is performing as well as possible, run the PPBM5 Benchmark
It will show you how well it is tuned to perform difficult effects like MBL or non-accelerated effects like Alpha Glow without rendering.
You can try to see if you have any improvement by setting your playback resolution to 1/2.