In some regions, Canon has included RemoteCapture DC software with the G10. On Windows, there's PSRemote.

I have no direct experience with gphoto2, but its idea seems to be quite simple, translating requested commands to camera-specific datagrams and as such the library itself is unlikely to be a major cause for slowness.

Rather, the G10 firmware seems to do full on-and-off cycle for each capture requested by computer, and this of course is much slower than shooting images manually. Perhaps CHDK would act more sensibly.

The easiest way to increase frame rate would be to capture video instead of still photos, and extract frames from that.

For still images, other than getting a faster camera, frame rate can be maximized by trying to spend less time for each shot, such as

• use lower resolution (JPEG, no RAW) to deal with less data;
• use manual exposure so there would be no need to measure light;
• use manual focus so there would be no need to focus;
• switch off instant viewing of captured photo;
• avoid using flash so its capacitors would not need refilling;
• use higher ISO or more light so you could use a faster shutter speed;
• use continuous shooting mode so the camera can optimize to deliver many shots quickly;
• leaving data in camera is likely faster than tethering, tethering via cable is likely faster than over Wi-Fi.