My solution was 1) reinstall pfSense 2.24, 2) observe browsing and website response, 3) allow program to download and install current version. Repeat Step 2. Install security update 2.3.1_1. Repeat Step 2. PIA was configured per guide and modified instructions. Repeat Step 2.
I can't describe it yet browsing 'feels' normal before upgrade to 2.3.
Initial upgrade to 2.3.1 from 2.2.6 failed. IIRC it required 3 attempts. I didn't realize it but there were big changes to 2.3 from 2.2.x.
IMO OpenVPN issues were triggered by PHP. Incremental updates did not properly address PHP.
Suggest reinstalling previous pfSense without configuring OpenVPN. Allow program to download and install current version, install security update(s), and configure OpenVPN.
Hope this helps.