go test ./... takes 35–45 seconds to complete

```
% make test
go test -count=1 ./...
?   	github.com/nishanths/exhaustive/cmd/exhaustive	[no test files]
ok  	github.com/nishanths/exhaustive	45.274s
%
```

Run a profiler and find out why. Is it simply a large number of tests, or does some of the source code have inherently poor performance?

