"Send to Compressor" Vs. "Compressor" Transcoding Time

Hi everybody,

When transcoding a H.264 video (1280x720; 25p; 1hr. approx.) to MPEG-2 using the default settings in Compressor, it takes around 2,5 hrs to complete the job.

However, I have realized that if I first import the H.264 media in FCPX (neither optimized nor proxy), create a project (default settings) with that media and then use the "Send to Compressor" command, it takes only about 20 min. to transcode it (same MPEG-2 default settings in Compressor).

Does anybody knows why this could happen? By the way, this issue is not only constrained to H.264 to MPEG-2. It happens with any transcode combination.

Many thanks for your help,

Miguel

Compressor 4.2.1

FCPX 10.2.2

OSX 10.11.2

MacBook Pro 2,2 GHz i7 Quad (early 2011); 500 GB SSD; 8 GB RAM; AMD Radeon HD 6750M