Yes, that fits with my own experience. I've not used Typed Racket itself, but I've used contracts in untyped Racket. I found them so slow that I ended up using a macro which discarded them unless it was a run of the test suite.
Figure 3 in that paper is enlightening: the fully typed version takes 0.7x as long as the untyped version, so Typed Racket is slightly faster than normal Racket. Most of the partially-typed versions take 50x to 100x as long, as you say, showing that it is indeed the contracts that slow everything down.
Figure 3 in that paper is enlightening: the fully typed version takes 0.7x as long as the untyped version, so Typed Racket is slightly faster than normal Racket. Most of the partially-typed versions take 50x to 100x as long, as you say, showing that it is indeed the contracts that slow everything down.