Scrolling and tabbing of the library list become too slow when waveform is hidden on Tango. It seems that symptons are the same as what MK-42 have reported at https://github.com/mixxxdj/mixxx/pull/1512
* my linux laptop (intel i5 1.8G, intel HD 4000) --> slowdown, except not using GL or GLSL for waveform type, or using "skin.xml" reverted before the commit "Tango: load waveforms as Singleton, display it with zero height below decks 1/2 to allow end-of-track warning when waveforms in splitter are hidden" contained in Pull #1512.
* my linux desktop (intel i3 2.6G, radeon HD 6459) --> no slowdown
Mixxx (current Master 2018-3-25) is build on my desktop (Debian GNU/Linux 9 stretch).
Depends: libasound2 (>= 1.0.16), libc6 (>= 2.22), libchromaprint1 (>= 1.3.2), libflac8 (>= 1.3.0), libgcc1 (>= 1:3.0), libgl1-mesa-glx | libgl1, libglib2.0-0 (>= 2.12.0), libglu1-mesa | libglu1, libhidapi-libusb0 (>= 0.8.0~rc1+git20140201.3a66d4e+dfsg), libid3tag0 (>= 0.15.1b), libmad0 (>= 0.15.1b-3), libogg0 (>= 1.0rc3), libopus0 (>= 1.1), libopusfile0 (>= 0.5), libportaudio2 (>= 19+svn20101113), libportmidi0, libprotobuf-lite10, libqt4-dbus (>= 4:4.5.3), libqt4-network (>= 4:4.5.3), libqt4-opengl (>= 4:4.6.1), libqt4-script (>= 4:4.7.0~beta1), libqt4-scripttools (>= 4:4.5.3), libqt4-sql (>= 4:4.5.3), libqt4-svg (>= 4:4.5.3), libqt4-test (>= 4:4.5.3), libqt4-xml (>= 4:4.5.3), libqtcore4 (>= 4:4.8.0), libqtgui4 (>= 4:4.8.0), librubberband2, libshout3, libsndfile1 (>= 1.0.20), libsoundtouch1 (>= 1.9.2), libsqlite3-0 (>= 3.5.9), libstdc++6 (>= 5.2), libtag1v5 (>= 1.11), libupower-glib3 (>= 0.99.0), libusb-1.0-0 (>= 2:1.0.8), libvamp-hostsdk3v5, libvamp-sdk2v5, libvorbis0a (>= 1.2.3), libvorbisenc2 (>= 1.1.2), libvorbisfile3 (>= 1.1.2), libx11-6, libqt4-xmlpatterns, libqt4-sql-sqlite
Thanks for reporting this.
On ubuntu studio 14.04 using a rt kernel I don't have any issues, and no change of CPU usage when toggling waveforms (RGB GL).
You use debian, so please test an official beta build (.deb) from the repository just to exclude any compiler/
If the issue persist, please check out the other skins, i.e. drag the waveform/deck splitter to zero in LateNight or Deere.
Also try to drag the unmaximized window up (keep Alt pressed and drag with mouse pointer) so that the waveforms are out of sight.