Yes, export to OME-TIFF should be in QuPath v0.2.0-m4. You can customize the options in the preferences (enter ‘ome’ in the search bar under Edit → Preferences…), e.g. to change the compression type, tile size and whether or not tiles are exported in parallel.
Parallelization can help a bit, although ultimately the tiles need to be written sequentially. Therefore it really helps to interleave requests for pixels from the file with writing to disk so that writing is the bottleneck.
In m4 you can also increase the available RAM, and also the proportion of memory given to tile caching - which will be especially important if you need to dynamically calculate the resolutions (as opposed to them being stored in the original file). If the tiles from the highest resolution are still present when writing the lower resolution then they can be used.
I still find writing images slower than I’d like, and I don’t know if it will handle your case well. But it’s probably worth a try to see how it compares with bfconvert.
For more information, see https://petebankhead.github.io/qupath/2019/08/20/fourth-milestone.html
Note also this script (described on the blog) that shows how to write an OME-TIFF in QuPath via a Groovy script, which may give more useful options (e.g. if channels should be interleaved or not).