I see, but why vmxnet3 instead of the native, and I guess more efficient, VirtIO type? You can limit it's bandwidth also but I guess will impact less the guest resources and so will increase overall performances
Don't ever use the "R" variant, they are optimized for Reading only and have poor write performances, you have to use the "M" (mixed, read/write) variant, like DC500M or the newer model DC600M, a little more expensive but with optimal I/O...