Nim (devel) compilation takes a very long time with option --gc:orc

[HJarausch]

I have a small source file (less than 200 lines) but which uses Weave, which is 
a complicated beast. Just trying to compile it I get
    
    
    nim c --threads:on -d:release Count_Reduction_WV_NL.nim  9.07s user 0.51s 
system 327% cpu 2.923 total
    
    
    Run

but **with --gc:arc**
    
    
    nim c --threads:on --gc:arc -d:release Count_Reduction_WV_NL.nim  898.88s 
user 0.70s system 100% cpu 14:51.44 total
    
    
    Run

This is nearly 305 times slower? Is this to be expected?
    
    
    nim -v
    Nim Compiler Version 1.5.1 [Linux: amd64]
    Compiled at 2021-04-07
    Copyright (c) 2006-2021 by Andreas Rumpf
    
    git hash: 834d5641e88b144c1cf94fa13f567b0a2acda977
    active boot switches: -d:release
    
    
    Run