[fpc-devel] Performance of string handling in trunk

[Michael Schnell]

On 06/20/2013 05:31 PM, luiz americo pereira camara wrote:
> The point is that i would expect a smaller performance hit when 
> there's no conversion going on. Something between 10% slower. In the 
> cited case is more than 50% slow.
As the "dynamic" types of (most) String Variables are already defined 
and known at compile time, and thus (usually) the library does not need 
to detect the encoding in realtime, the performance hit should be close 
to zero, as long as the same String encoding is used as with the 
non-(DXE-compatible)-Unicode project with the same source code.

OTOH, if the former version used 1-Byte-Strings (ANSI or UTF-8) and the 
new version used 16 or 32 bit Strings (UTF-16 or UTF32) I would expect a 
severe performance hit as well because more bytes need to be moved and 
because the cache gets a lot more tight because of the double memory usage.

-Michael
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