Addons start slow

With current developer branch Leia, I have the problem that kodi addons start very slow (on raspberry pi 2). This is not limited to a specific addon. My log is created for youtube addon, with popcornmix newclock5 (66be47), but is also slow with latest commits.

Addons start very slow, because CPythonInvoker needs very much time until ‘Python Interpreter Initialized’ (17s):

Code:
15:21:45.518 T:1407181808    INFO: initializing python engine.
15:21:45.518 T:1407181808   DEBUG: CPythonInvoker(24, /home/osmc/.kodi/addons/plugin.video.youtube/default.py): start processing
...
15:22:02.699 T:1407181808   DEBUG: -->Python Interpreter Initialized<--

And 13s:

Code:
15:22:02.701 T:1407181808   DEBUG: CPythonInvoker(24, /home/osmc/.kodi/addons/plugin.video.youtube/default.py): instantiating addon using automatically obtained id of "plugin.video.youtube" dependent on version 2.19.0 of the xbmc.python api
...
15:22:22.644 T:1407181808   DEBUG: [plugin.video.youtube] Using API key set: 4
15:22:22.759 T:1407181808   DEBUG: [plugin.video.youtube] Starting Kodion framework by bromix...
15:22:22.879 T:1407181808  NOTICE: [plugin.video.youtube] Running: YouTube (5.3.12) on Krypton (Kodi-18.0) with Python 2.7.9

Debug Overlay in general shows a high cpu usage, even on ‘homescreen’ – (CPU-KODI 124%)

Any idea how to fix?

Full log:
http://pastebin.com/MzLq0gZH