Claes Redestad - Software Engineer

Claes has been working as an OpenJDK performance engineer at Oracle since 2012, benchmarking, developing and improving the runtime in many ways small and large ever since. Living in Stockholm, Sweden, Claes enjoys good coffee, bad puns, and rugby.

Posts

• Performance Improvements in JDK 25 on October 20, 2025 JDK 25 Performance
• Performance Improvements in JDK 24 on March 19, 2025 JDK 24 Performance
• Faster Charset Encoding on October 17, 2021 Performance JDK 17 JDK 18
• Faster Charset Decoding on February 24, 2021 JDK 17 Performance
• Reducing MD5 (and SHA) overheads on February 14, 2021 Performance Security
• Investigating MD5 overheads on January 4, 2021 Performance JDK 16 Security
• Towards OpenJDK 17 on December 6, 2020 Performance Leyden JDK 17 JDK 16
• Zip lookups - a word from the sponsor on April 27, 2020 Performance JDK 15
• OpenJDK Startup - Late 2019 Edition on November 20, 2019 Performance JDK 13 JDK 14
• String concatenation, redux on May 14, 2019 Performance
• cljinit woes on February 11, 2019 Performance

Videos

• Java Performance Update: From JDK 21 to JDK 25 on March 8, 2026 JDK 25 Performance
• Rethinking Java String Concatenation #JVMLS on August 19, 2024 Core Libraries JDK 23 JDK 24 Performance
• Heap Archiving on February 7, 2020 Performance