I just tested this app briefly with Regshot; Only Firewall settings created in registry, all configuration files created in apps folder. Memory usage ~5MB.
Tixati is a new and powerful BitTorrent client. 100% free, contains no spyware, no ads, and no gimmicks Windows and Linux native versions available
Ultra-fast downloading algorithms
DHT, PEX, and Magnet Link support
Super-efficient peer selection and choking
Advanced bandwidth control and charting
RC4 connection encryption for added security
Advanced views of peers, pieces, files, and trackers
Detailed event logging for all transfers and individual peers
Tixati v1.42 Portable Edition
This is a special build of Tixati meant to run on USB flash-drives. It is self-contained and keeps all configuration files within it's executable folder, and stores all paths in a format relative to the executable binary file. Executable binaries for both Linux and Windows are included, and the configuration files are platform-neutral.
The UI is fully customizable; e.g. Color Scheme, Custom Colors, Widget Styles, Behavior, Output Formatting.
Highly configurable settings throughout the program.
Portable and User friendly!