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If you have a WordPress VPS or Dedicated hosting, you may use an in-memory caching solution rather than exclusively caching to disk. In-memory caching takes advantage of the much faster read/write speeds and lower latency of accessing data from system memory compared to disk-based alternatives.
In-memory caching solutions may also be ideal if your disk cache is likely to fill your disk with cache files, and you would prefer to have an automatic maximum limit on the amount of storage that is possible for caching to consume.
Alternative PHP Cache (APC / APCu)
APC refers to Alternative PHP Cache which provides in-memory Opcode caching and a key-value store for looking up cached items. This is largely deprecated in favor of modern Opcode Caching mechanisms, as APC is not supported in the PHP 7.x branch.
APCu is similar to APC, though in order to support modern variants of PHP it is stripped of Opcode Caching and only provides the in-memory key-value store mechanisms. When paired with modern Opcode Caching mechanisms it can provide the functionality originally provided by APC, though it should only be used when you require having a limited cache size.
APC/APCu is not stable when a lot of memory is allocated. In cases where you are caching a small amount of data, APC/APCu may be the ideal method for single-instance hosting platforms such as VPS or Dedicated hosting.
eAccelerator is an in-memory Opcode caching solution that supports the PHP 4.x and 5.x major versions. This is largely deprecated in favor of modern Opcode Caching mechanisms, as eAccelerator is not supported in the PHP 7.x branch.
XCache is an in-memory Opcode caching solution that supports up to the PHP 5.6 release. This is largely deprecated in favor of modern Opcode Caching mechanisms, as XCache is not supported in the PHP 7.x branch.
WinCache (Recommended for Windows-based Environments)
WinCache is an extension for Microsoft IIS which provides in-memory Opcode caching and currently supports up to IIS 10 as of 04/30/2019. Check the official Microsoft product page for the latest information.
These solutions are mostly intended for use in hosting plans that provide a single account where you either have elevated privileges to install custom software, or a hosting provider that is able to make these changes for you.
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