 
 
 
 
 
   
Cost
Cost
- Interpreters avoid compilation but exec is slow
- SIMD two main sources of additional waste 
- Synchronisation means short programs take as long to execute as long programs. 
- Most operations (80%) are not wanted and their results are thrown away. 
 
- Leafs access data and so are much more expensive than functions?
- A multiplication takes only 4 clock cycles = 3nS 
- Main memory read takes up to 300 clock cycles 
- 50% of trees are leafs. 
- so cost is dominated by leafs not functions? 
 
- We accept other interpreter overheads (eg Lisp, Perl, Python, PHP), so why not SIMD overhead