What software is the quickest to convert video files to iphone format?

I've been using any video converter and free video to iphone converter. Both very slow, it takes up to an hour to convert a 20 mins.wmv or.avi.

Are there any faster alternatives? And does that depend on whether I choose to convert to iphone 4 or iphone 5 format? I've tried the latter so can it be that it would be quicker for iphone 4?

Try handbrake (http://handbrake.fr). Please note that actual conversion speed depends mostly on the processor's speed and number of cores, not the program you're using. Also the bitrate (or conversion quality) affects the time it takes to convert a video file.

Any Video Converter.
Download from here - http://www.any-video-converter.com/download-avc-free.php

Http://www.freemake.com/free_video_converter/

You'd better use a professional video converter which can quickly and perfectly convert videos for your iphone with the original excellent video quality. Generally, such video converter has fast speed and easy to use. Below is one of such video converters' download link.
By the way, if you use a Mac computer, you must use the mac version video converter for iPhone.

Handbrake is good. And you also can try aneesoft video converter which I used well.

Really fast video conversion speed, you can consider snowfox total media converter, convert an hour video to iphone 5 just need 15 mins.

Try Freemake video converter, this one is nice and totally free.

Try format factory, which is a free video converter and supports converting videos of various formats. I always use it to convert videos, and think it works effectively. Maybe it would be the right program for you as well.

Conversion speed is affected by speed/type of your cpu and ram so same software can run smoother on faster computers, it depends on both cpu architecture, type and length/format of an input file. You can try this software to see a difference.

I'd like to recommend this iPhone converter to you, I always use it to convert DVD movie and video to mp4 video to my iPhone, the conversion speed is really fast and the video quality is pretty good. But it's not free. You may download it for a try, and here is a step by step guide about how to use it.