diff --git a/Cargo.toml b/Cargo.toml
index 7c99af2..43b62c2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,6 +18,14 @@ codegen-units = 1
 [profile.dev]
 opt-level = 1
 
+# desktop builds (tools/build_desktop.py): optimised like release, but compiled on all cores
+# (several codegen units, thin LTO); release keeps one unit and full LTO for the smallest,
+# fastest WASM
+[profile.desktop]
+inherits = "release"
+lto = "thin"
+codegen-units = 16
+
 # desktop builds: system file dialog (xdg portal on Linux) and sound output
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 rfd = { version = "0.17", default-features = false, features = ["xdg-portal"] }
diff --git a/tools/build_desktop.py b/tools/build_desktop.py
index 19bd957..1e9b529 100644
--- a/tools/build_desktop.py
+++ b/tools/build_desktop.py
@@ -149,8 +149,8 @@ def build_linux(ver):
     # libasound is only linked by name: its own glibc references are the user's system's business
     env["RUSTFLAGS"] = (env.get("RUSTFLAGS", "") + " -C link-arg=-Wl,--allow-shlib-undefined").strip()
     log(f"Linux build (glibc {GLIBC})")
-    run([cargo(), "zigbuild", "--release", "--target", f"x86_64-unknown-linux-gnu.{GLIBC}"], env=env)
-    binary = ROOT / "target" / "x86_64-unknown-linux-gnu" / "release" / "dungeoncraft"
+    run([cargo(), "zigbuild", "--profile", "desktop", "--target", f"x86_64-unknown-linux-gnu.{GLIBC}"], env=env)
+    binary = ROOT / "target" / "x86_64-unknown-linux-gnu" / "desktop" / "dungeoncraft"
 
     appdir = ROOT / "target" / "AppDir"
     shutil.rmtree(appdir, ignore_errors=True)
@@ -175,9 +175,9 @@ def build_windows(ver):
     need_target("x86_64-pc-windows-gnu")
     env = zig_env()
     log("Windows build")
-    run([cargo(), "zigbuild", "--release", "--target", "x86_64-pc-windows-gnu"], env=env)
+    run([cargo(), "zigbuild", "--profile", "desktop", "--target", "x86_64-pc-windows-gnu"], env=env)
     out = DIST / f"DungeonCraft-{ver}-windows-x64.exe"
-    shutil.copy2(ROOT / "target" / "x86_64-pc-windows-gnu" / "release" / "dungeoncraft.exe", out)
+    shutil.copy2(ROOT / "target" / "x86_64-pc-windows-gnu" / "desktop" / "dungeoncraft.exe", out)
     return out
 
 
@@ -193,13 +193,13 @@ def build_macos(ver):
     env["MACOSX_DEPLOYMENT_TARGET"] = "11.0"
     for t in arches:
         log(f"macOS build {t}")
-        run([cargo(), "build", "--release", "--target", t], env=env)
+        run([cargo(), "build", "--profile", "desktop", "--target", t], env=env)
 
     app = ROOT / "target" / "DungeonCraft.app"
     shutil.rmtree(app, ignore_errors=True)
     (app / "Contents" / "MacOS").mkdir(parents=True)
     (app / "Contents" / "Resources").mkdir(parents=True)
-    run(["lipo", "-create", "-output", app / "Contents" / "MacOS" / "DungeonCraft"] + [ROOT / "target" / t / "release" / "dungeoncraft" for t in arches])
+    run(["lipo", "-create", "-output", app / "Contents" / "MacOS" / "DungeonCraft"] + [ROOT / "target" / t / "desktop" / "dungeoncraft" for t in arches])
     short = ver.lstrip("v").replace("-", ".")
     (app / "Contents" / "Info.plist").write_text(INFO_PLIST.format(short=short, version=ver), encoding="utf-8")