Typescript 3.4 (RC) includes a new "incremental" flag: https://devblogs.microsoft.com/typescript/announcing-typescript-3-4-rc/

I've updated to 3.4 and set this flag to true.

If I do tsc -p tsconfig.json then the build cache is generated and subsequent calls are much faster.

But if I run it through webpack (which is using ts-loader), then the build cache is not generated and subsequent calls take about the same time as previously.

Does ts-loader need to be changed in order to support it?