R2012a says: "Note: findstr will be removed in a future release. Use strfind instead." This is a reason to replace findstr in code, which will be around for some years in the future.
And strfind is somewhat faster
n2 = 1e6;
a = 'a':'p';
buf = a( randi( [1,16], [1,n2] ) );
str = reshape( buf, 1, [] );
pattern = a( randi( [1,16], [1,4] ) );
tic, ix1 = strfind( str, pattern ); toc
tic, ix2 = findstr( str, pattern ); toc
all( ix1==ix2 )
returns
Elapsed time is 0.001971 seconds.
Elapsed time is 0.003049 seconds.
ans =
1
