update per 4638

Author: wileyj

.cargo/config

@@ -2,6 +2,11 @@
 stacks-node = "run --package stacks-node --"
 fmt-stacks = "fmt -- --config group_imports=StdExternalCrate,imports_granularity=Module"
 
+# Uncomment to improve performance slightly, at the cost of portability
+#   * Note that native binaries may not run on CPUs that are different from the build machine
+# [build]
+# rustflags = ["-Ctarget-cpu=native"]
+
 # Needed by perf to generate flamegraphs.
 #[target.x86_64-unknown-linux-gnu]
 #linker = "/usr/bin/clang"

README.md

@@ -49,6 +49,19 @@ cargo build --release
 cargo build --profile release-lite
 ```
 
+_Note on building_: you may set `RUSTFLAGS` to build binaries for your native cpu:
+
+```
+RUSTFLAGS="-Ctarget-cpu=native"
+```
+
+or uncomment these lines in `./cargo/config`:
+
+```
+# [build]
+# rustflags = ["-Ctarget-cpu=native"]
+```
+
 ## Testing
 
 **Run the tests:**