Saving to hdf5 is very slow (Python freezing)

I’m trying to save bottleneck values to a newly created hdf5 file.
The bottleneck values come in batches of shape (120,10,10, 2048).
Saving one alone batch is taking up more than 16 gigs and python seems to be freezing at that one batch. Based on recent findings (see update, it seems hdf5 taking up large memory is okay, but the freezing part seems to be a glitch.

How to build a SystemTray app for Windows?

I usually work on a Linux system, but I have a situation where I need to write a client app that would run on windows as a service. Can someone help me or direct, on how to build a system tray app (for example like dropbox) for the windows environment, which gets started on OS startup and the icon sits in the TaskBar and on clicking the app icon presents a menu.