JTosca uses version 1.14 of SnakeYAML parser. I recommend upgrading to the latest version.

Benchmarks I ran on SnakeYAML a while ago showed an about two-fold improvement in read performance even in 1.18 compared to 1.17. Write performance improvements were more modest, but still noticeable (>10%). There are also numerous functionality and security fixes https://bitbucket.org/asomov/snakeyaml/wiki/Changes.