Hello,
Lazarus is built from SVN sources. I had exact same problem on Lazarus 1.8.0RC3 and 1.6 some version.
Component bar is very large at the time I start Lazarus. Oddly enough, this does not happen always. But, a lot of time I get that.
Problem is as you can see in attached picture.
If I swithch to another component tab (not matters which one) problem solves.
Is there anything I can try or bring in here like more data?
Thanks.