Evaluate LTO

[bolinfest]

Consider adding the following to Cargo.toml to improve performance / reduce binary size:

[profile.release]
lto = true

[sharkdp]

Benchmark on a random subset of files in the bat repo.

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
./bat-no-lto --color=always src/*.rs README.md Cargo.toml	231.8 ± 2.2	227.4	235.3	1.09 ± 0.01
./bat-lto --color=always src/*.rs README.md Cargo.toml	213.5 ± 1.8	209.7	216.1	1.00

That's a solid 10% speedup. Nice.

Compile time (release build from scratch, including all dependencies):

• without LTO: 2min 31sec
• with LTO: 3min 7sec

[sharkdp]

This has been released in bat 0.13.

[tbillington]

@sharkdp You may be able to reduce the compile time hit with thin over true/fat, though probably should bench that first 😀

https://doc.rust-lang.org/cargo/reference/profiles.html#lto