refactor: performance improvement to linq query

Author: Squaretechre

README.md

@@ -80,4 +80,8 @@ The callback principle, pass `OperationB` as an argument to `OperationA` and let
 	- Better idea:	Picking - Yields `O(N)` and execution time should be proportional to the length of the sequence.
 							- Aggregate() walks the sequence once
 - Loops and branching instructions are infrastructure. Don't deal with infrastructure, deal with functional requirements.
-	- Pick an available painter with the minimum estimate cost.
+	- Pick an available painter with the minimum estimate cost.
+
+### Advice
+
+- Implement extension methods only to wrap infrastructural code which is likely to never change.