performance improvement and no crash in debug mode

simu/src/cpu.rs

@@ -174,7 +174,7 @@ impl<'a, 'b> Computer<'a, 'b> {
     pub fn new(filename: String, screen: &'b Mutex<Pixels<'a>>, key: &'b AtomicU32) -> Self {
         let mut new = Self {
             creation: Instant::now(),
-            ram: Box::new([0; 0x01000000 / 4]),
+            ram: unsafe { Box::new_zeroed().assume_init() },
             regs: [0; 16],
             pc: 0,
             sp: 0,