Slow internet speed for program over VPN on my router C6250

Recently with working from home, I have to connect to a remote desktop from home over the internet using a VPN.  When I get into this desktop, I run a pretty heavy software program.  On my home network, which gets 100Mbps download and 10Mbps upload on wifi, this program lags severely.  However, on a friend's home network (same ISP) which gets about 15Mbps download and 6Mbps upload, the program runs beautifully.  I can't seem to connect the dots with this problem and have done everything I can think of.  I've not changed any settings with my router and the firmware is up to date.  I tried factory resetting the router, unplugging it, everything short of getting a new one.  It simply doesn't make sense that an 8 month old router with great internet speeds works perfectly with everything except for this one application when an older, cheaper, slower Netgear router works perfectly fine.  Any other ideas?