diff --git a/content/notes/22-performance-and-security.md b/content/notes/22-performance-and-security.md
index 751b4c524..468c4afb2 100644
--- a/content/notes/22-performance-and-security.md
+++ b/content/notes/22-performance-and-security.md
@@ -16,4 +16,22 @@ tags:
 			- statements are accurate and generated on time
 		- quickly, accurate, and on time need to be operationalised, measured, and tested.
 
-WHy are they important
+Why are they important
+- vital quality factor
+- infosystems are wide and varied
+- wide range of performance characteristics
+
+- impact of changing requirements, e.g., adding a new module
+- need to consider (often conflicting) organisational priorities
+- critical to unambiguously document and agree
+
+Things to consider
+- can interact and conflict with each other
+	- accuracy vs speed
+	- speed vs space
+	- often a trade-off or compromise
+- selectig best developent techniques for taget system
+	- algorithms
+	- data structures
+	- languages and frameworkds
+	- constraints of target platform
\ No newline at end of file