There is no one switch to turn off all optimizations - an interesting idea, but technically a little tough because the optimizer was not originally written to support that. There are probably 200+ individual switches to turn off specific pieces of the optimizer. Most are undocumented dml_options "bits" like the ones suggested, and some are documented - for example, you can turn off the join optimizer with a boolean option "join_optinizer" set to off. Note: I doubt this is a join optimizer issue.
Another less likely possibility is that query tree parallelism is taking long. That can be disabled with dml_options8=8.
As Chris suggested, there could be cache issues (not enough memory in the main cache or -iqlm might cause problems with lookup FP indexes). Another tool Chris suggested is to reduce the number of columns. Many columns can have a big performance effect.
What IQ version is this?