diff --git a/Makefile.pre.in b/Makefile.pre.in
index d54a098..5aeb502 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -210,7 +210,9 @@
 TCLTK_LIBS=	@TCLTK_LIBS@
 
 # The task to run while instrument when building the profile-opt target
-PROFILE_TASK=-m test.regrtest --pgo
+# We exclude unittests with -x that take a rediculious amount of time to
+# run in the instrumented training build or do not provide much value.
+PROFILE_TASK=-m test.regrtest --pgo -x test_asyncore test_gdb test_multiprocessing test_subprocess
 
 # report files for gcov / lcov coverage report
 COVERAGE_INFO=	$(abs_builddir)/coverage.info