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--- performance [2019/08/01 12:26] – [Tip #7 REPEAT ... UNTIL is faster than FOR ... NEXT] neils
+++ performance [2019/09/03 08:55] – [Tip #9: Know the optimizer] neils
@@ Line 97: / Line 97: @@
     inc i!
   until i! = 100
+==== Tip #9: Use LSHIFT() and RSHIFT() ====
+It's much faster to multiply or divide by powers of two using bit shifting operations. Use [[lshift|LSHIFT()]] and [[rshift|RSHIFT()]] whenever you can.
+==== Tip #10: Know the optimizer ====
+**XC=BASIC** features a built-in optimizer that replaces commonly used program sequences with faster opcode sequences. To make good use of the optimizer, bear in mind the following program structures that can be optimized:
+  * Value assignment of bytes and integers
+  * Addition of bytes and integers
+  * Subtraction of bytes and integers
+  * Comparison of bytes, e. g. ''IF x! > 5 THEN ...''
+  * ''IF'', ''WHILE'' and ''UNTIL'' statements with byte type comparison as condition, e .g ''WHILE x! <= 255''
+  * Array access of byte type arrays with byte type index
+  * Bitwise operators on bytes
+  * POKE and PEEK (they're the fastest when using constant addresses)
+The following are not optimized at all:
+  * Operations on floating point types
+  * I/O commands like ''PRINT'', etc.
+  * Convenience commands like ''TEXTAT''