Greetings! You are correct in that extractors can sometime incur severe performance penalties. Extractors are a legacy feature that predates Processing Pipelines.
I recommend exploring the use of Processing Pipeines and using those in place of extractors. This blog post is a great place to get started: https://graylog.org/post/graylog-parsing-rules-and-ai-oh-my/ . Let us know if you have any specific questions.