Is this much slower than direct Access?
RewriteEngine On
RewriteRule (.*) http://localhost:23232/$1 [P]
It wouldn't be much slower. It would only differ by the tiny fraction it takes for Apache to proxy your request which compared to the time it takes for Node.js to process your request is most likely even hard to measure.
However, you'd probably want to use ProxyPass and ProxyPassReverse instead of a rewrite so that Apache acts as a real proxy instead.