You can have a look in the settings if all the RAM is made available to SNAP. It is explained here: SNAP memory issues while importing S3 products
If you have 16 GB, marpet suggests a maximum value of -J-Xmx13G, for 32 GB you could then set it to 25G Bicubic and bilinear resampling method problem in Reprojection Tool
Another possible reason for the differences: Maybe the Windows 7 one is 32 bit only?