I am new to using Zen Cart and I am in the process of moving my store to Zen. I currently have more than 300,000 products in the products table. The site itself is very quick except for search. Home page, product pages, etc load in less than one second. However, searching a product can take up to 20 seconds and obviously that is not sufficient. Does anyone have any suggestions to improve the speed other than rewriting search? Are there any addon's available that replace/reinforce the current search code?

Below are some server/system specs:
Zen Cart Version: 1.3.9g
Server: Dedicated Linux CENTOS Server
Intel Xeon 3210 Quadcore
4 GB RAM


Thanks!