ffmeg on i686

[chrishell <chris@chrishell.de>]

Hello out there,
I have a bad performance with multimedia players like VLC since summer
last year on my Thinkpad X60 with testing (Intel(R) Core(TM) Duo CPU and
Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller).
VLC complains amongs others this:
libva info: va_getDriverName() returns 0
libva info: Trying to open /usr/lib/i386-linux-gnu/dri/i915_drv_video.so
libva info: va_openDriver() returns -1
[b2bb5a00] vdpau_avcodec generic error: decoder profile not supported: 8
libva info: VA-API version 0.39.4
libva info: va_getDriverName() returns 0
libva info: Trying to open /usr/lib/i386-linux-gnu/dri/i915_drv_video.so
libva info: va_openDriver() returns -1
[b44465f0] avcodec decoder error: more than 5 seconds of late video ->
dropping frame (computer too slow ?)
....

I suspect this has something to do with ffmpeg since it began with the
chaging from libav to ffmpeg. So I envoked ffprobe. I guess you know
this very well but I give you the output:
ffprobe version 3.2.2-1 Copyright (c) 2007-2016 the FFmpeg developers
  built with gcc 6.2.1 (Debian 6.2.1-5) 20161124
  configuration: --prefix=/usr --extra-version=1 --toolchain=hardened
--libdir=/usr/lib/i386-linux-gnu --incdir=/usr/include/i386-linux-gnu
--enable-gpl --disable-stripping --enable-avresample --enable-avisynth
--enable-gnutls --enable-ladspa --enable-libass --enable-libbluray
--enable-libbs2b --enable-libcaca --enable-libcdio --enable-libebur128
--enable-libflite --enable-libfontconfig --enable-libfreetype
--enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug
--enable-libmp3lame --enable-libopenjpeg --enable-libopus
--enable-libpulse --enable-librubberband --enable-libshine
--enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh
--enable-libtheora --enable-libtwolame --enable-libvorbis
--enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265
--enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx
--enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394
--enable-libiec61883 --enable-libopencv --enable-frei0r --enable-libx264
--enable-chromaprint --enable-shared
  libavutil      55. 34.100 / 55. 34.100
  libavcodec     57. 64.101 / 57. 64.101
  libavformat    57. 56.100 / 57. 56.100
  libavdevice    57.  1.100 / 57.  1.100
  libavfilter     6. 65.100 /  6. 65.100
  libavresample   3.  1.  0 /  3.  1.  0
  libswscale      4.  2.100 /  4.  2.100
  libswresample   2.  3.100 /  2.  3.100
  libpostproc    54.  1.100 / 54.  1.100

So my questions are: is ffmpeg the reason for the performance drop on my
X60? And if so, is it possible to take the source package of ffmpeg
modify it with other optimizations in order to build a ffmpeg, which is
more usable for my 32Bit system?
(complement: I can watch most of films, streams within Firefox without loss)

Thank you in advance.

Best Regards Christian