oddstrings2.m

#import <Foundation/Foundation.h>
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        const long count = 10000000;
        const char *str1 = "hellohello"; //fits in a tagged pointer
        const char *str2 = "hellohelQo"; //at this character count, can only fit in a tagged pointer by using <8 bits per character, which requires dropping less frequently used chars like 'Q'
        const char *str3 = "Northern Sami"; //this string is encountered frequently enough that it's baked into a perfect hash table in CoreFoundation
        const char *str4 = "hellohellü"; //this string can't be tagged *and* can't be stored using an ASCII backing store

        NSDate *start = [NSDate date];
        for (long i = 0; i < count; i++) {
            (void)[[NSString alloc] initWithUTF8String:str1];
        }
        NSTimeInterval t = -[start timeIntervalSinceNow];
        NSLog(@"Time to allocate @\"%s\" %ld times was %f seconds", str1, count, t);
        start = [NSDate date];
        for (long i = 0; i < count; i++) {
            (void)[[NSString alloc] initWithUTF8String:str2];
        }
        t = -[start timeIntervalSinceNow];
        NSLog(@"Time to allocate @\"%s\" %ld times was %f seconds", str2, count, t);
        start = [NSDate date];
        for (long i = 0; i < count; i++) {
            (void)[[NSString alloc] initWithUTF8String:str3];
        }
        t = -[start timeIntervalSinceNow];
        NSLog(@"Time to allocate @\"%s\" %ld times was %f seconds", str3, count, t);
        start = [NSDate date];
        for (long i = 0; i < count; i++) {
            (void)[[NSString alloc] initWithUTF8String:str4];
        }
        t = -[start timeIntervalSinceNow];
        NSLog(@"Time to allocate @\"%@\" %ld times was %f seconds", [[NSString alloc] initWithUTF8String:str4], count, t);
    }
    return 0;
}

/* On a 2.5GHz 2014 Retina MacBook Pro running 10.12.x, compiled with clang -fobjc-arc -framework Foundation -Os oddstrings.m -o odd, this produces:
2016-11-30 11:17:12.120 odd[85251:12659427] Time to allocate @"hellohello" 10000000 times was 0.385130 seconds
2016-11-30 11:17:13.957 odd[85251:12659427] Time to allocate @"hellohelQo" 10000000 times was 1.834985 seconds
2016-11-30 11:17:14.582 odd[85251:12659427] Time to allocate @"Northern Sami" 10000000 times was 0.625479 seconds
2016-11-30 11:17:17.261 odd[85251:12659427] Time to allocate @"hellohellü" 10000000 times was 2.678630 seconds
*/