Hey I’m not sure too! 
@Lennox - My old HP G60-120EM Intel(R) Core™ Duo 2.00Ghz 3.00 GB RAM runing Trisquel GNU-Linux 8.0 having not noticed any delays I clicked the calculator – instant. Clicked LibreOffice Calc spreadsheet – ok perhaps one second. So I thought; this calculator is so basic let’s install something scientific: found gnome calculator and installed it in under a minute via dongle connection – up and running just fine in any of the five modes – no problemo! Closed it down then fired it up – instant. 
Have stayed with ubuntu 16.04 (kept updated) for now on my faster Dell Latitude Intel(R) Core™2 Quad CPU Q8300 @ 2.5GHz 4.0GB RAM it too has no problem with calculators and happily runs 3D FreeCAD and wine Serif PhotoPlus.
Tried many, many distros lately and think MX was about best – might jump too. Like Trisquel ethos; so it will remain on the old HP – roll on version 9! Favorite toy at moment is Tails 4.2.2 on a stick packing Tor Browser; so fast and silent that I keep forgetting that I am only in 4GiB RAM. 
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