Performance Improvements

Performance improvements

Here we enumerate all of the areas where Mixxx can be optimized, roughly in order of importance. The more things we can complete on this list, the more machines Mixxx can run on, and the larger our user base.

CPU

(Anything found that wastes CPU time should be listed here)

• Line 881 in enginebuffer.cpp process() fires continuously while Mixxx is idle: fixed by rryan

// Stopped. Wheel, jog and scratch controller all scrub through audio.
rate=(wheel->get()*40.+m_pControlScratch->get()+m_jogfilter->filter(m_pJog->get()))*baserate; //*10.;
m_pJog->set(0.);

• Line 43 in controlobjectthreadmain.cpp eventFilter() also fires incessantly while idle:

emit(valueChanged(ce->value()));

• Line 96 in controlpotmeter.cpp setValueFromThread() also fires very often while idle:

emit(valueChanged(m_dValue));

• Line 107 in controlpotmeter.cpp setValueFromEngine() also fires very often while idle:

emit(valueChangedFromEngine(m_dValue));

• EQ code takes up 50% of our current CPU usage on a Pentium 4 (with static EQs! HQ eqs are even slower...)

Time-critical code

(Please list all time-critical code sections/functions here to be considered for assembly language reimplementation.)

• EQ code
• EngineBufferScale: EngineBufferScaleLinear and EngineBufferScaleST

For reference:

• Intel64 & IA-32 manuals
• AMD64 manuals

Memory

(Anything that wastes memory by inefficient storage (where unnecessary) or leaks goes here)

• Currently loading four two copies of MP3 files into memory. (r2509 in 1.7 removes the second copy as soon as the Analyser is done with it, plugging a big leak.)
• Vinyl control leaks part of the lookup table, or something like that when it gets deleted/recreated
• SoundSource's should use memory mapped IO. Making that cross platform is tricky.