Hi mcb100,
The slow response and lack of resiliency of memory foam is a common complaint with memory foam mattresses when it comes to sex (see post #2 here).
As zexpress mentioned you can add a latex topper on top of your mattress which is a much more resilient type of foam that will help add some “bounce” to some degree although it won’t remove the “feel” of the memory foam completely. A thicker layer of latex will have more effect on modifying the feel and response of the memory foam underneath it than a thinner layer.
Your mattress would only have memory foam on the top layers and the bottom layer would be polyfoam (not memory foam) so if you wanted to remove the effect of the memory foam completely you could also turn your mattress over and use a topper on the bottom (although the bottom would be the support foam which would be much firmer so you may need a thicker topper to provide the pressure relief that you need than you would on the top of the mattress).
Post #2 here and the topper guidelines it links to includes some guidelines for choosing a topper and also includes a link to the better online sources for toppers I’m aware of as well.
Phoenix