I don't use C1, I'm surprised that an image takes 30 seconds to pop up on screen.
On my Canon I shoot RAW + JPEG (Large, Medium, or Small JPEG.) If your camera can create a RAW + JPEG at the same time, you could just check the JPEG, avoiding the overhead of the conversion of the RAW.
In the past, maybe 4-5 years ago, I used BreezeBrowser to sort and preview images. It had a pretty small footprint and fast performance working from the JPEG. They also have a tethered camera control tool, but it is really for DSLR's only, mostly Canon and Nikon, as is their RAW conversion.
In the tethered tool, you had the option of storing images on the CF card, on the laptop, or both. I believe you also had the option of transferring only the JPEG to the laptop without the RAW.
I'll load trial copies of those to test with my Canon for comparison with C1 and the Canon software. That might give an idea of the relative range of options to look at in other manufacturers software. (I will buy a MFDB again in September or October, once I start working again and open a new studio. Off work right now.)