If your portable package allows mod additions, drop the OptiFine 1.5.2 JAR file into your core game files. OptiFine drastically reduces CPU overhead and can double your framerate on low-end machines.
java -Xmx1024M -Xms512M -jar Minecraft.jar unblocked games minecraft 152 portable
If file-sharing sites are blocked at your school, upload the portable ZIP file to your personal Google Drive. School networks rarely block Google Workspace domains, allowing you to download your files easily. Optimizing Performance on School or Work PCs If your portable package allows mod additions, drop