Will Brokenbourgh

@tryashtar, the link to 'Potion effects' wiki in the issue you linked to has no content.  How would I know about this?  The game should present a warning if you use a multiplier over 127.  I agree with some of the posters in that thread: the game should warn that any multiplier over 127 is wrong.  Smells like a bug to me.

I'm on a 2018 Mac mini with a fast-ish 3.2 GHz Intel Core i7 processor, 16 GB RAM and 20w22a is crazy laggy compared to happily playable a snapshot or two ago.  My mini feels like a hot-plate after playing 20w22a.  I don't install resource packs or mods, so hopefully this issue will get worked out.

I have now compiled the necessary lwjgl libs and pointed Minecraft to them, but unfortunately it crashes hard...

[22:52:16] [Render thread/INFO]: Setting user: XXXXXXXXXXX
#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00000008015a6b64, pid=93033, tid=101298
#
# JRE version: OpenJDK Runtime Environment (11.0.5+8) (build 11.0.5+8-1)
# Java VM: OpenJDK 64-Bit Server VM (11.0.5+8-1, mixed mode, tiered, compressed oops, g1 gc, bsd-amd64)
# Problematic frame:
# V [libjvm.so+0x7a6b64] _ZN14AccessInternal19PostRuntimeDispatchIN12G1BarrierSet13AccessBarrierILm1097844ES1_EELNS_11BarrierTypeE2ELm1097844EE18oop_access_barrierEPv+0x4
#
# Core dump will be written. Default location: /usr/home/will/minecraft/java.core
#
# An error report file with more information is saved as:
# /usr/home/will/minecraft/hs_err_pid93033.log
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
#
/usr/home/will/.minecraft/myfunruntime.sh: line 48: 93033 Abort trap (core dumped) java -Dorg.lwjgl.librarypath=/usr/local/lib/lwjgl2.9.3 -Djava.library.path=/usr/local/openjdk11/lib ${args[@]}

I will post the logs and core separately.

Using the 'legacy' launcher mentioned here  I have bypassed this issue and instead have encountered a lwjgl issue.  I will follow the advice here  to try and get Minecraft working on FreeBSD, as it did before recent changes.

Looks like the reporter hasn't attached anything yet.  The attached log file is what I get when running the Launcher on FreeBSD 12.1.  There was no 'launcher_log.txt' in the ~/.minecraft directory, so I took the log from the launcher's log window.