I've used the PEAR DB library for over the past ten years.
Whilst building a failover infrastructure project, I noticed that performance going cross-site was poor.
I eventually worked out that the MySQL library as part of PEAR DB doesn't turn on compression.
Turning it on is relatively simple - just a few lines to change in the mysqli.php file:
And the performance difference is quite striking.
Here's the network traffic stats from a MySQL server hosted on Digital Ocean and AWS Lightsail: