Wow ancient thread. Just to clarify oversampling in general should not require realtime playback.
Its just a DSP process that requires more computation. If anything its more costly to do during realtime playback.
When we do plugin upsampling the results are identical during slow and fast bounce.
This thread makes me wonder if we should be setting the render flag on even when we are doing realtime bounces because some plugins seem notice that and change behavior. hmmm...