[mythtv-users] 2005 laptop stutters after upgrade from 0.27 to 0.28

[faginbagin]

Yep, I've still got a few old laptops that have been working quite well 
as frontends. But one isn't performing quite as well with mythtv 0.28 
and mythbuntu 16.04 as it is with mythtv 0.27 and mythbuntu 12.04. So, 
I'm trying to understand why, and whether there's anything I can do to 
get it to perform running 0.28 as well as it does running 0.27. The 
laptop and the master backend have multiple boot partitions, so that's 
how I switch back and forth between 0.27 and 0.28

I see slight but noticeable stuttering during panning scenes when I 
playback standard definition H.264 video on 0.28 but not when I play 
back the same video on 0.27. It's not CPU bound, the CPU hovers around 
30% to 35% on both versions and might be using a tad less CPU on 0.28 as 
it does on 0.27.

The laptop is a Dell Inspiron B130 with an Intel Celeron M 1.5 GHz CPU 
and an Intel Mobile 915GM/GMS/910GML Express Graphics Controller. The 
display is 1280x800 resolution. It's configured to use the Slim playback 
profile on both 0.27 and 0.28, as defined in the database migrated from 
0.27 to 0.28.

I have compared mythfrontend logs using -v general,playback at the 
default info level. I can see no meaningful difference in the log 
output. I've hesitated to try the debug level, for fear that might push 
the CPU and/or disk to work too hard, although maybe that should be my 
next step?

I have compared Xorg.0.log on both OSs, and only see slight differences 
like version numbers, and a handful of different messages that I suspect 
are due to logging changes in source and not meaningful.

FWIW, the laptop can play 720p and 1080i MPEG2 transport streams 
smoothly in both 0.27 and 0.28. But it cannot play high definition H.264 
content on either, where it's definitely CPU bound. I've also got a 
couple of circa 2004 thinkpads with Pentium M CPUs and Radeon GPUs that 
CAN handle the SD H.264 in both 0.27 and 0.28 environments. It's just 
this Dell that's keeping me from cutting over to 0.28.

Has anyone else noticed a degradation in performance on older hardware 
after upgrading?

Any suggestions on how to identify the cause, e.g. OS module, X driver 
or mythtv?