Quote Originally Posted by savage
My understanding is that [pascal]<> nil[/pascal] is faster due to it being a a simple pointer test, while [pascal]is[/pascal] would incurr more RTTI calls.
The difference is subtle, but "is" is implemented by analysing the virtual method tables, not the runtime type information. So, if you want to avoid RTTI bloat, you can still safely use "is".

"Is" is certainly slower than a nil check.