Controls whether LZMA compression is performed inside the main compiler process or in a separate process.

Using a separate process for LZMA compression allows the compressor to allocate larger amounts of memory, which makes it possible for higher LZMADictionarySize and LZMANumBlockThreads settings to be used. Additionally, on 64-bit Windows (x64), a small increase in compression speed may be observed.

On 64-bit Windows (x64), there are no limitations on the amount of memory the compressor may use, as it runs inside a native 64-bit process. On 32-bit Windows, however, due to address space constraints, typically only about 1.5 GB is available for use by the compressor.

A value of yes enables the use of a 64-bit process on 64-bit Windows (x64), and a 32-bit process on 32-bit Windows.

A value of x86 enables the use of a 32-bit process only (normally only useful for debugging purposes).

A value of no disables the use of a separate process for LZMA compression.

Note that this directive only affects the compression of files specified in the [Files] section; compression of Setup's internal structures is always performed inside the main compiler process.