-fexternal-interpreter slow for profiling with template haskell

I'm trying to build the following program (in Foo.hs) with profiling enabled:

{-# LANGUAGE TemplateHaskell #-}
main = print $([| 10 |])

With the "alternate object file suffix" method, I have correct build time:

$ time ghc -prof -osuf o_p Foo.hs
[1 of 1] Compiling Main             ( Foo.hs, Foo.o_p )
Linking Foo ...

real	0m1.698s
user	0m1.518s
sys	0m0.184s

However with -fexternal-interpreter, times are abysmally slow:

$ time ghc -prof -fexternal-interpreter -osuf "p_o" Foo.hs
[1 of 1] Compiling Main             ( Foo.hs, Foo.p_o )
Linking Foo ...

real	0m26.077s
user	0m1.531s
sys	0m0.190s

I'm using ghc-8.6.3 on nixos.

Trac metadata

Trac field	Value
Version	8.6.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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