gradle-build-performance

Gradle Build Performance

This reference covers the workflow discipline plus the patterns that move the needle and are easy to get wrong, not the standard knobs (org.gradle.caching, org.gradle.parallel, org.gradle.jvmargs, android.nonTransitiveRClass, kapt → ksp).

Workflow: measure a baseline (clean + incremental) → ./gradlew assembleDebug --scan (or --profile for a no-upload report) → find the slow phase (configuration / execution / dependency resolution) in the Build Scan timeline → apply one optimization at a time → measure again. Batching changes means you never learn what helped.

Configuration phase — the cheapest wins

• Configuration cache (org.gradle.configuration-cache=true, AGP 8+) skips the entire configuration phase when inputs are unchanged. Start with org.gradle.configuration-cache.problems=warn, move to fail once clean.
• No I/O during configuration. A file("version.txt").readText(), a network call, or exec {} at configuration time breaks the configuration cache and slows every build — defer it to execution: providers.fileContents(layout.projectDirectory.file("version.txt")).asText.
• Lazy task registration — tasks.register("x") { … } (configured only if it's in the execution graph), never tasks.create("x") { … } (eager).
• Convention plugins, not subprojects {} / allprojects {} — those root-build blocks eagerly evaluate every subproject. Move shared config into convention plugins (see android-skills:android-gradle-logic).

kapt → KSP (mandatory on AGP 9)

KSP is ~2× faster than kapt, and AGP 9 makes the migration mandatory — it has built-in Kotlin support and org.jetbrains.kotlin.kapt is incompatible with it. Migrate to KSP (requires KSP 2.3.1+ on AGP 9; Hilt / Room / Moshi all support it), or fall back to com.android.legacy-kapt (same version as AGP) for annotation processors with no KSP equivalent. See JetBrains' kotlin-tooling-agp9-migration skill for the broader AGP 9 mechanics.

Dependency resolution

• Pin versions — a dynamic 1.0.+ or -SNAPSHOT forces a network resolution check on every build. Pin 1.2.3.
• Repository order — Gradle checks repositories in declaration order; put the most-used first (google() then mavenCentral(), third-party last).

A reasonable gradle.properties baseline

org.gradle.configuration-cache=true
org.gradle.caching=true
org.gradle.parallel=true
org.gradle.jvmargs=-Xmx4g -XX:+UseParallelGC
android.nonTransitiveRClass=true