diff --git a/README.md b/README.md
index aaba16a..a929433 100644
--- a/README.md
+++ b/README.md
@@ -8,101 +8,72 @@ The test
 --------
 
 Compiles 64 small binaries with [bazel-zig-cc][1] and [llvm14][2]. The tests
-were run on an x86_64 8-core machine running Ubuntu 22.04. The llvm's sysroot
-is this:
+were run on an x86_64 8-core machine running Ubuntu 22.04.
 
-    sha256 = "84656a6df544ecef62169cfe3ab6e41bb4346a62d3ba2a045dc5a0a2ecea94a3",
-    urls = ["https://commondatastorage.googleapis.com/chrome-linux-sysroot/toolchain/2202c161310ffde63729f29d27fe7bb24a0bc540/debian_stretch_amd64_sysroot.tar.xz"],
+Results
+-------
 
-... but with extra ~8k files, so the number of files in the sysroot is exactly
-the same as in zig sdk.
+    Benchmark 1: bazel build --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux --spawn_strategy=local //...
+      Time (mean ± σ):      9.257 s ±  0.287 s    [User: 0.083 s, System: 0.026 s]
+      Range (min … max):    8.818 s …  9.515 s    5 runs
 
-Baseline
---------
+    Benchmark 2: bazel build --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28 --spawn_strategy=local //...
+      Time (mean ± σ):      9.613 s ±  0.214 s    [User: 0.077 s, System: 0.038 s]
+      Range (min … max):    9.418 s …  9.866 s    5 runs
 
-Baseline llvm14 without sandbox: 12 seconds:
+    Benchmark 3: bazel build --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux --spawn_strategy=sandboxed --experimental_reuse_sandbox_directories //...
+      Time (mean ± σ):     13.314 s ±  0.201 s    [User: 0.109 s, System: 0.028 s]
+      Range (min … max):   13.093 s … 13.536 s    5 runs
 
-    bazel build --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux //:zigzag-0
-    bazel clean; bazel shutdown
-    bazel --batch build --spawn_strategy=local --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux ...
-    INFO: Elapsed time: 13.268s, Critical Path: 1.19s
+    Benchmark 4: bazel build --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28 --spawn_strategy=sandboxed --experimental_reuse_sandbox_directories //...
+      Time (mean ± σ):     13.829 s ±  0.376 s    [User: 0.093 s, System: 0.046 s]
+      Range (min … max):   13.573 s … 14.489 s    5 runs
 
-zig cc without the sandbox. 15 seconds:
+    Benchmark 5: bazel build --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux --spawn_strategy=sandboxed //...
+      Time (mean ± σ):     35.101 s ±  0.365 s    [User: 0.103 s, System: 0.028 s]
+      Range (min … max):   34.747 s … 35.673 s    5 runs
 
-    bazel build --spawn_strategy=local --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28 //:zigzag-0
-    bazel clean; bazel shutdown
-    bazel --batch build --spawn_strategy=local --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28 ...
-    INFO: Elapsed time: 23.836s, Critical Path: 3.47s
+    Benchmark 6: bazel build --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28 --spawn_strategy=sandboxed //...
+      Time (mean ± σ):     21.071 s ±  0.378 s    [User: 0.091 s, System: 0.034 s]
+      Range (min … max):   20.611 s … 21.635 s    5 runs
 
-Cost of Sandbox
----------------
-
-llvm 14:
-
-    bazel build --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux //:zigzag-0
-    bazel clean; bazel shutdown
-    bazel --batch build --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux ...
-    INFO: Elapsed time: 89.776s, Critical Path: 12.01s
-
-zig cc:
-
-    bazel build --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28 //:zigzag-0
-    bazel clean; bazel shutdown
-    bazel --batch build --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28 ...
-    INFO: Elapsed time: 58.919s, Critical Path: 8.38s
-
-Possible mitigation: Sandboxfs
-------------------------------
-
-No dice.
-
-llvm 14: does not build at all:
-
-    $ bazel build --experimental_sandboxfs_path=sandboxfs --experimental_use_sandboxfs --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux //:zigzag-0
-    ERROR: /code/test-zigcc/BUILD:4:14: Compiling main.cc failed: (Exit 5): cc_wrapper.sh failed: error executing command external/llvm_toolchain_with_sysroot/bin/cc_wrapper.sh -U_FORTIFY_SOURCE '--target=x86_64-unknown-linux-gnu' -U_FORTIFY_SOURCE -fstack-protector -fno-omit-frame-pointer -fcolor-diagnostics -Wall ... (remaining 29 arguments skipped)
-
-    Use --sandbox_debug to see verbose messages from the sandbox and retain the sandbox build root for debugging
-    ERROR: could not find clang; PWD="/proc/self/cwd"; PATH="<...>".
-    Target //:zigzag-0 failed to build
-    Use --verbose_failures to see the command lines of failed build steps.
-    INFO: Elapsed time: 7.578s, Critical Path: 0.26s
-    INFO: 3 processes: 3 internal.
-    FAILED: Build did NOT complete successfully
+    Summary
+                                      'bazel build --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux --spawn_strategy=local //...' ran
+        1.04 ± 0.04 times faster than 'bazel build --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28              --spawn_strategy=local //...'
+        1.44 ± 0.05 times faster than 'bazel build --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux --spawn_strategy=sandboxed --experimental_reuse_sandbox_directories //...'
+        1.49 ± 0.06 times faster than 'bazel build --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28              --spawn_strategy=sandboxed --experimental_reuse_sandbox_directories //...'
+        2.28 ± 0.08 times faster than 'bazel build --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28              --spawn_strategy=sandboxed //...'
+        3.79 ± 0.12 times faster than 'bazel build --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux --spawn_strategy=sandboxed //...'
 
 
-zig cc:
+| Command | Mean [s] | Min [s] | Max [s] | Relative |
+|:---|---:|---:|---:|---:|
+| `bazel build --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux --spawn_strategy=local                                              //...` |  9.257 ± 0.287 |  8.818 |  9.515 | 1.00 |
+| `bazel build --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28              --spawn_strategy=local                                              //...` |  9.613 ± 0.214 |  9.418 |  9.866 | 1.04 ± 0.04 |
+| `bazel build --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux --spawn_strategy=sandboxed --experimental_reuse_sandbox_directories //...` | 13.314 ± 0.201 | 13.093 | 13.536 | 1.44 ± 0.05 |
+| `bazel build --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28              --spawn_strategy=sandboxed --experimental_reuse_sandbox_directories //...` | 13.829 ± 0.376 | 13.573 | 14.489 | 1.49 ± 0.06 |
+| `bazel build --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux --spawn_strategy=sandboxed                                          //...` | 35.101 ± 0.365 | 34.747 | 35.673 | 3.79 ± 0.12 |
+| `bazel build --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28              --spawn_strategy=sandboxed                                          //...` | 21.071 ± 0.378 | 20.611 | 21.635 | 2.28 ± 0.08 |
 
-    bazel build --experimental_sandboxfs_path=sandboxfs --experimental_use_sandboxfs --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28 //:zigzag-0
-    bazel clean; bazel shutdown
-    bazel --batch build --experimental_sandboxfs_path=sandboxfs --experimental_use_sandboxfs --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28 ...
-    INFO: Elapsed time: 126.613s, Critical Path: 17.63s
-
-
-Possible mitigation: `--experimental_reuse_sandbox_directories`
----------------------------------------------------------------
-
-Dice.
-
-llvm 14:
-
-    bazel build --experimental_reuse_sandbox_directories --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux //:zigzag-0
-    bazel clean; bazel shutdown
-    bazel --batch build --experimental_reuse_sandbox_directories --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux ...
-    INFO: Elapsed time: 18.335s, Critical Path: 2.00s
-
-zig cc:
-
-    bazel build --experimental_reuse_sandbox_directories --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28 //:zigzag-0
-    bazel clean; bazel shutdown
-    bazel --batch build --experimental_reuse_sandbox_directories --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28 ...
-    INFO: Elapsed time: 34.777s, Critical Path: 4.71s
+Explanation:
 
+* `--spawn_strategy=local` is the baseline. This is the fastest possible
+  approach (no sandbox), but does never runs in production.
+* `--spawn_strategy=sandboxed` is the default for Bazel. This is what happens
+  if one does not pass any arguments.
+* `--spawn_strategy=sandboxed --experimental_reuse_sandbox_directories` is an
+  optimization which is meaningful on sandboxes with many files. As of Bazel 6
+  this has been [promoted to stable][3], so safe to use and, as one can see in
+  the numbers, recommended with both bazel-zig-cc and a nontrivial sysroot. As
+  a result, this is the most important benchmark to look at.
 
 Flame graphs and discussion
 ---------------------------
 
-Flame graphs and more tests are in results/. As of 2022-12-11 most of the
-overhead comes from creating and deleting the sandboxes.
+Flame graphs in results/. Only of historical interest, because the original
+performance issues have been resolved with a combination of zig and
+bazel-zig-cc changes.
 
 [1]: https://sr.ht/~motiejus/bazel-zig-cc
 [2]: https://github.com/grailbio/bazel-toolchain
+[3]: https://github.com/bazelbuild/bazel/issues/16138
diff --git a/results/profile.sh b/results/profile.sh
index 0a5454c..ffb0f7b 100755
--- a/results/profile.sh
+++ b/results/profile.sh
@@ -1,13 +1,23 @@
 #!/bin/bash
 set -xeuo pipefail
 
+# set to 1 to enable profiling
+profile=
+
 _build() {
+    if [[ "$profile" == 1 ]]; then
+        perf=(perf record --call-graph=dwarf -g -o "$HOME/$name.data")
+    else
+        perf=()
+    fi
+
     name=$1
     shift
-                                                            bazel         build    --color=no --curses=no "$@" //:zigzag-0
-                                                            bazel         clean    --color=no --curses=no
-                                                            bazel         shutdown --color=no --curses=no
-    perf record --call-graph=dwarf -g -o "$HOME/$name.data" bazel --batch build    --color=no --curses=no "$@" ...
+                 bazel         build    --color=no --curses=no "$@" //:zigzag-0
+                 bazel         clean    --color=no --curses=no
+                 bazel         shutdown --color=no --curses=no
+     ( "${perf[@]}" bazel --batch build --color=no --curses=no "$@" ... ) |& \
+         tee "results/${name}.log"
 }
 
 _build zigcc-nosandbox          --spawn_strategy=local                    --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28
@@ -17,7 +27,9 @@ _build llvm                                                               --extr
 _build zigcc-reuse-sandbox-dirs  --experimental_reuse_sandbox_directories --platforms=@zig_sdk//libc_aware/platform:linux_amd64_gnu.2.28
 _build llvm-reuse-sandbox-dirs   --experimental_reuse_sandbox_directories --extra_toolchains=@llvm_toolchain_with_sysroot//:cc-toolchain-x86_64-linux
 
-for d in $HOME/*.data; do
-    f=$(basename "$d")
-    echo "perf script -i $d | inferno-collapse-perf | inferno-flamegraph > results/${f%data}svg"
-done | parallel -v --eta
+if [[ $profile == 1 ]]; then
+    for d in $HOME/*.data; do
+        f=$(basename "$d")
+        echo "perf script -i $d | inferno-collapse-perf | inferno-flamegraph > results/${f%data}svg"
+    done | parallel -v --eta
+fi