"Rene Lamontagne" wrote

| I exported the registry to a blank folder and checked it's size it was
| 377 MB.

As Paul said, the Registry is files. If you export
to .reg files you're creating a text-based record
that can be used to import that data again. It
won't be the same size because it's a text file
and the Registry is a database. In other words,
what you export is comparable to a CSV file.

Also, Registry cleaners usually focus on a few
things. Most notably entries under HKCR for COM
libraries that may be gone. There may also be entries
for uninstalled software. But those entries are a
tiny portion of the total Registry. They're harmless.
And in some cases they may be useful: If you decide
to reinstall a program later you might be glad your
settings are still there.

Sysinternals used to have a program to defrag
the Registry. I don't know if it still exists or whether
such a task would still be useful, but it seems a
defrag would make more sense than just removing
a handful of entries.