What you are describing is fine - you should be climbing at best climb speed, regardless of weight.
Being low is dangerous. The aim is to get high, as quickly as possible. It is actually the decreased performance when 2-up which is more of an issue than the increased rate when solo
although not actually a problem as long as you are within the aircraft's w+b limitations.
Enjoy the extra performance - it'll seem normal once you're used to it!
FFF
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