Your b2evolution version: 1.8.1
Your level of knowledge of Internet technologies: Advanced Knowledge
Link to your b2evolution blog: http://www.got1mag.com

PHP Version:
MySQL Version: 4.1.21

What actions led up to your current issue?
My blog has high CPU usage and slow performance of session queries. It will go down intermittently when traffic is high.

What have you tried to solve the issue?
Creating indexes on sess_lastseen and sess_key

Description and Message

Since upgrading to 1.8.1, I experience high CPU usage and slow performance of session queries on my blog site. It will go down intermittently when traffic is high.

When checking the mysql log, I find that most slow queries are SELECT queries on the evo_sessions table.

I tried creating indexes on the sess_key and sess_lastseen columns. Thereafter I see slight improvement, but I am not sure because the effect is not apparent. I still see a "CPU quota exceeded" message occasionally.

However, checking on the mysql log again, I find that the INSERT queries are taking up longer time (7sec or higher). I do not see as many slow SELECT queries, but occasionally a SELECT query can take up to 21 sec.

My question is: Is creating index a right thing to do? How else can I speed up performance?

Thank you.