That doesn't sound good
When somebody complains about their new system being slower than they expected (or slower than the old one)... my first question used to be what the startup parameters are and how they compared to the old box, then more questions about the setup. Now my first question is whether the new box is NUMA or not.
All that being said... it can "work" depending on...
- How many reads you do and how big your -B is going to be
- How much faster the new cores/disks are than the old system
- What your current bottlenecks are
But it is more brute force of newer hardware (that is running slower than it should) compared to ancient hardware.