Is the process for a combination visitor visa longer than the usual visitor visa process?

No. The process for a combination visitor visa (B-1/B-2) is not longer than the standard visitor visa process.

I don't believe so. The application, interview, and processing timeline are typically the same as for a regular visitor visa.

Nah. Pretty much the same. In fact, i've heard that most visitor visas issued by U.S. Department of State are already issued as B-1/B-2 combination visas, allowing travel for both business (B-1) and tourism (B-2) under the same visa.