mysql or mysqli. whats better?

[didimo]

background
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i have a large web application, with over 20000 users (about 100 people using at any time)

now im making a new version in PHP 5.1 (on FC3 linux, apache2, mysql 5 server)
of the web app

i use PEARB (and other pear libraries alongside my php5 classes) for database connection


question
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the app works fine with MYSQL and MYSQLI

which should i use? which is faster?

for me performance is the target thats why im recoding the system into php5
im also using alot of object caching to reduce database load

oh and almost forgot;
current database size is 800mb
im reduced that to 100mb by changing schema and using caching

[longneck]

i've never tested them for speed. with pear::db, it very easy to change. so why don't you set it for one, then change it the next week to the other?

[didimo]

thats what i was going to do, im just wondering if anyone has any facts or experience regading speed comparison (if they exist)

[DMacedo]

Making it simple, MySQL is old, while MySQLi is new, so that should already point to you towards which should be best

But talking really, if you don't need the advanced features of MySQLi, I would stick to MySQL due to portability between older versions of PHP. I can imabine there could be true significant improvements in MySQLi.

My view is that MySQLi is better, but still has to prove itself, and I can't benchmark everything just to prove my views.