执行时间不会减少更高的计算机配置PHP

Question

I have a corpus consists of over 100 million Unicode words and the file size is around 2GB. I wrote a code to count the frequency of each word in the corpus in PHP. The code is running in Mozilla Firefox Browser with XAMPP local server. The code takes 90MB of texts each time and counts frequency and then take the next 90MB(since it was not taking the whole file at a time). When I ran the code in a PC with 6GB RAM and Core 2 Duo processor, it took 2 days to complete 20% of the work. Then, with another PC with 8GB RAM and Core i5 processor it took the same time. Finally, I used a server PC with 32GB RAM and Xeon Silver 4114 Processor it is taking almost the same amount of time. This makes me realize something is restricting using resources from PC. I don't get it. Is there any speed limitation on browsers or local server? Please help.