Could you please submit a bug-report, as described in this document:
After you submitted the report, you receive a confirmation email with a Case number. Please post this bug-report Case number here (in this thread) for Unity staff to pick up.
Let me say that’s totally not expected to see raycasts slower in 18.3. Like others said, please do send out your test project and we’ll investigate. Thanks!
I made another project from scratch and it looks like I am seeing the faster queries now… There was something strange going on with the initial one I was using.