They're certainly not blazing, especially not if running on SD-based storage, which is horrifically slow at doing the intense small random writes this type of process entails. But this doesn't really say anything about OpenBSD, only about this type of hardware. It would after all fall equally short if you were to link the Linux kernel under Linux, or the FreeBSD kernel under FreeBSD, or start Chromium with two dozen tabs to be restored, etc.
Try a Raspberry Pi.