Q for Informix Gurus : Informix/ESQL-C performance

Hi Gurus, Where can I get info about how to performance tune an Informix/ESQL-C program? I have a complex program which talks to several other processes & databases. It seems to be running slower than expected. I'm in the process of collecting all relevant information about this - so for now I'm just asking a general question without providing specific details. I'll post more info shortly about the actual programs involved. I'm fairly new to Informix too, so no flames please ! (And yes, I'm in the process of reading all the manuals I can lay my hands on ;) I'm looking at things like use of indexes, the optimizer, SET EXPLAIN PLAN, etc. Configuration : HP 9000 HP-UX Ver 10.10 Informix Ver 5.0 Informix 4GL Ver 4.1 C compiler & runtime library (HP-UX) TCP/IP on HP-UX Informix Star Thanks in advance Vasudev Ram Infosys