Webel: Mathematica: TIP: Maintain a Package library of Quantity variables for frequently used units using a naming convention unit$[unitSymbol] and unit[DescriptiveName] or unit[Acronym]
Mathematica: Use of UnitConvert (or even just multiplication or division by a unit Quantity) MASSIVELY slows the calculations down!
Mathematica: The awesome Quantity system for values with units is everything the SysMLv1.x Quantity/Unit system should have been (and hopefully SysMLv2 will be). But it comes at a high performance cost!