Searching for specific words in 220 files, totaling 8 Mb, on a moderately-sized VPS with 4/2200 Mhz and 8 GB of RAM should not be a laborious process for PHP. PHP is capable of handling regular expressions efficiently, especially with small-sized files. However, the performance also depends on the complexity of the regular expressions and the specific implementation of your code. It is always recommended to test your code with a subset of files and measure its performance before applying it to the entire dataset.

In general, searching through small-sized files using regular expressions in PHP should not pose significant performance issues. PHP is a popular and widely-used programming language with efficient regular expression support.

The size of the files, totaling 8 Mb, is relatively small, and PHP should have no trouble handling them. The processing time for searching through these files will likely be fast, especially considering the VPS specifications you mentioned (4/2200 Mhz and 8 GB RAM).

However, as I mentioned before, the complexity of the regular expressions used and the specific implementation of your code can affect performance. If the regular expressions are very complex or the code is inefficiently written, it could potentially impact the search process.

To optimize performance, you could consider techniques such as caching results, indexing, or using more specific matching patterns to narrow down the search space. Additionally, utilizing multi-threading or parallel processing can help improve efficiency if the PHP interpreter and your system environment support it.

Here are some additional points to consider regarding searching for specific words in multiple files using regular expressions in PHP:

1. File I/O: The performance of reading and accessing files can also affect the overall search process. While the file size is small, if there are a large number of files, the I/O overhead may become significant. Consider optimizing file access by minimizing disk seeks, utilizing caching techniques, or organizing files in a way that improves read times.

2. Regular Expression Complexity: Regular expressions can become computationally expensive, especially if they are complex and involve backtracking. Be mindful of the complexity of your regular expressions and, if possible, optimize them to ensure efficient pattern matching. Using more specific patterns, avoiding excessive backtracking, and leveraging optimizations like lazy quantifiers can help improve performance.

3. Memory Usage: While 8 GB of RAM should be sufficient for processing the given dataset, keep in mind that PHP's memory footprint can increase depending on factors such as the number and size of variables, the regular expressions used, and any additional libraries or dependencies involved. Monitor memory usage and consider optimizing memory consumption if necessary.

4. Utilize Multithreading or Parallel Processing: If you have access to PHP extensions like pthreads or if your PHP version supports parallel processing, you can potentially speed up the search process by utilizing multiple threads or processes to search through the files concurrently.