I was afraid that would happen.
I said that from my own experience. I have an IBM X41 tablet computer that was an alright little machine. I bought a 128GB SSD drive for it and it was an "Oh My Gosh" change. Now, it is so fast that I can see that the video system sucks. I couldn't before. The thing is just plain fast now.
For yourself, perhaps you can find a small SSD on eBay just to try it out. I think XP can run with an 8Gb drive. They're cheap at that size. They seem to get faster at or above 32 GB. (About $100.00).
Otherwise, check your BIOS for control of the L1, L2 cache. If set wrong, it will be quite slower than expected.