From NSIS Wiki
You can recompile NSIS with a custom configuration to remove features you are not using (to decrease the overhead size), to enable features that are not enabled by default (like advanced logging) or to change advanced settings of compression methods and variables. For available configurations, use scons --help before building.
For the users without a building environment, some special builds of makensis.exe are provided here. These builds are only compatible with NSIS 2.51 (older versions). Always make sure you extract the stubs files as well as they are part of makensis.
This build includes advanced logging features that allow you create an exact log of all installer actions (see the users manual for details). You can use it if you want testers or users to send installation reports.
scons NSIS_CONFIG_LOG=yes PREFIX=C:\somewhere install-compiler install-stubs
If you are working with large strings use this build which has a maximum string length of 8192 bytes instead of the default of 1024 bytes.
scons NSIS_MAX_STRLEN=8192 PREFIX=C:\somewhere install-compiler install-stubs