Johnwolf
Make sure your body firmware (fw) is at least 3.1.. If I remember latest is 3.2. If your lens fw is out of date, the body sw will detect and warn u at startup.
How responsive the af is based on both the camera body digital processing power, the mass of the lens material the af motor needs to move and the specific design of the af motor itself. The 18, 35 and 60 were first gen lens designs and they tend to be slower then say the newer 18-55 kit zoom for example. Of the three original lenses, the 18 is slightly faster and the 60 is the slowest.
The newest camera body, xt1, should be able to make the af speed of the 35 faster due to better CPU and digital hw.
I have both a GR and xp1. The GR is faster than a 35 w/ xp1. The 18-55 is pretty close to the GR, I can't remember which is faster.
The Fuji cameras will hunt if they c too much bland little to no contrast in the frame.. But most contrast detact af will do the same except those that have have detect cells as well. Look for strong lines in your picture for the af patch to use. Also u can adjust the size of the af patch when using evf or LCD by using the af button on the left side and the knurl above the 4 way. Depending on situations I will sometimes use a 30-45 degree angle of the line in question to get the af to lock, then reframe for final shot. This is because the Fuji af sensor is sensitive to horizontal vs vertical lines..
In terms of street, a technique I know some people use is to go manual focus, use the afl button to af lock on a location and wait for people to walk into the zone. Or just setup zone/scale focus.
Hope that helps
Gary