Is there a way to make FFmpeg seek faster to an end of file on a network share?

Is there a way to make FFmpeg seek faster to an end of file on a network share?

I'm using ffmpeg to generate image previews from flv videos. The OS is Debian 5 and it's the apt version of ffmpeg. The flv files are located on a NAS share that is mounted as NFS. Getting the thumbnails from the beggining of the flvs is pretty fast but is very slow when seeking above 10 minutes into the video. I call ffmpeg from python like so: