Update 1: Added results for the original version and initial improvements.
Update 2: Added results from tbench1-infinite.pl using Game::Life::Infinite::Board.
Update 3: Added results for C++, Organism.h and tbench1.cpp.

In this thread, we've learned that pack i2 is faster than pack ii. Furthermor, functions having inner loops benefit greatly by inlining critical paths. In essence this is what we've done. The pack i2 solution fully optimized is found here, by tybalt89. The mapping of two numbers into one can be found here. Similarly, a shorter implementation by tybalt89 is found here. The fastest time was noted for each run with nothing else running in the background.

The maximum key length for $c, obtained separately, is 7, 12, and 18 for pack i2, the mapping of two numbers, and the shorter solution by tybalt89, respectively. The fix for the latter solution, when running cperl on 64-bit hardware, is using 30 bits instead of 32, described here.

The x and y tmp files were made using eyepopslikeamosquito's createblinker.pl script, found at the top of this thread.

$ perl createblinker.pl 500000 -900000 100 >x.tmp 2>y.tmp
[download]

Benchmark results were captured on a 2.6 GHz laptop (i7 Haswell). I apologize for not having something older to benchmark on. If anything, the OP's machine is faster than mine. ;-)

Results:

c++              138 MB    4 secs

               mem size   v5.26.0   v5.24.2   v5.22.4

infinite       7,548 MB  122 secs  119 secs  133 secs
original         704 MB  167 secs  168 secs  180 secs
improvements     744 MB   57 secs   57 secs   63 secs
optimized i2   1,543 MB   38 secs   39 secs   40 secs
2 nums into 1  1,510 MB   39 secs   40 secs   42 secs
shorter impl   1,661 MB   40 secs   42 secs   44 secs
[download]

cperl:

$ /opt/cperl-5.24.3c/bin/cperl -I. tbench1.pl x.tmp 2
cell count at start = 1500000
run benchmark for 2 ticks
cell count at end = 1500000
time taken: 116 secs   - infinite board
time taken: 163 secs   - original
time taken:  54 secs   - improvements
time taken:  36 secs   - optimized pack i2
time taken:  37 secs   - two numbers into one
time taken:  37 secs   - shorter implementation
[download]

Pack returns unreadable data, but is fast. Readable keys may be preferred for storing into a DB. Stringification "$x:$y" is one way. Unfortunately, that requires split to extract the values and a text field versus numeric if storing into a DB. Bit manipulation is another way.

Running Game::Life::Infinite::Board consumes lots of memory. If possible, check for 8 ~ 10 gigabytes of available memory to minimize the OS from swapping. It also takes ~ 10 seconds during global cleanup while exiting.

eyepopslikeamosquito, infinite isn't running ~ 2x slower as reported here for 1.5 million cells. My laptop has 1600 MHz RAM and verified available memory before running.

Regards, Mario