set of <code>CXXFLAGS</code> and <code>LDFLAGS</code> flags can be turned on by setting <code>STAN_CPP_OPTIMS=true</code>
in the <code>make/local</code> file. These are tested compiler and link-time optimizations that can speed up execution
of certain models. We have observed speedups up to 15 percent, but this depends on the model, operating system
and hardware used. The use of these flags does considerably slow down compilation, so they are not used by default.</p>
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