Is it normal for toolchain to spends 30 seconds unpacking every time?

I am using the toolchain feature to download the necessary jvm automatically for a build:

pluginManager.withPlugin('java') {
  java {
    toolchain {
      languageVersion = JavaLanguageVersion.of(8)
      vendor = JvmVendorSpec.ADOPTOPENJDK

However, every time it needs the toolchain, e.g. running tests, it spends ~30 seconds unpacking the toolchain archive:

> Provisioning toolchain adoptopenjdk-8-x64-linux.tar.gz > Unpacking toolchain archive

Is this normal? I would expect it to unpack it once and re-use the same unpacked archive. Adding 30 seconds to every test run is quite a productivity killer when you are iterating on individual tests.