SNAP multi-size mosaic processor too slow?

When I process 6 S2 zip files for the neigbouring datastrips of the same orbit with SNAP multisize mosaic processor, it will take extremely long time ,almost take 3 or more days, but similar mosaicking withENVI will take about 30 minutes or less than one hour (tested with 10m bands). In fact , I want to mosaic S2 data for more than 20 consecutive or neighbouring datastrips of the same orbit within 2~4 hours timespan, but it seems SNAP can’t sustain this processing load. Can anyone provide more efficient way or walkround about this requirement? Thanks.