I believe the limitation is 50mb compressed/250mb uncompressed. I've never deployed a Java Lambda that's bigger than 20mb though so I've not hit that limitation.

I'll admit that on slow internet connections, uploading a JAR to deploy can be a bit slow though. We have a Jenkins CI build pipeline that automates this process, it builds the JAR (running unit tests etc), then uploads it to S3 and uses AWS Cloudformation to make the Lambda point to the new JAR in S3.