Advice on side gig – How to cope

I accepted a side job that will keep me occupied for about 3-4 hours a week but I am not sure whether I should tell my boss. Note that I am the only foreigner in my team. The idea is to work remote the day and then compensate by starting earlier and/or finishing later.

  • My company allows side jobs and there are no regulations whatsoever.
  • My contract is discretionary (no minimum number of hours need to be worked)
  • Now I have many 'dead' hours without a clear goal or task. This side job will not make my performance any different, aside from blocking my calendar for meetings.
  • KPIs are fluffy and it is hard to determine when the job for the day is done.
  • Some of my coworkers seem to be constantly searching for things to appear busy,

My boss is a difficult person and he recently complained that I account less hours of work than my coworkers (even though I work 40-45h/week). I have been doing all that I can, but even so he seems to think I don't work as much as my coworkers and/or don't deliver enough. His direction is ambiguous and has gets angry and frustrated for no reason during almost any conversation.

The idea of being "hiding" makes me feel a bit anxious, so I thought about saying something like "due to personal reasons I will be away a few hours on X day o the week", but I fear that consequences can be worse.

Thoughts?

by Xaletcaro