could PHP benefit from strict typing?

i was just thinking the other day about loosely typed scripting languages, like PHP, and pondering how much extra work the parser must go through to track, test and convert data types. this is one of the key appeals of PHP, so i'm not suggesting PHP should be strictly typed, i'd hate that too. But if there were an optional method of using strict typing in cases where performance is an issue, could it create a significant performance improvement? i was thinking something along the lines of: string $mystring = 'hello world'; int $myint = 5; $myint = 70; // ok $myint = 'blah blah'; // error int $somevar = $myint + $mystring; // error bool $mybool = 'some string'; // error $thisvar = 'any type'; // regular, variant typed variable it's quite possible i have no clue and this wouldnt help one bit, just a thought -Rob