Examine the following Rust code snippet that uses Arc<Mutex<Vec<i32>>> to share data between threads. The code is intended to aggregate the sum of squares from 0 to 100 across four threads, but it occasionally panics or produces incorrect results. Identify the specific location and nature of the race condition or deadlock risk. Rewrite the code to ensure thread safety and correctness without using global variables. Explain why your changes resolve the issue and discuss the performance implications of locking vs. lock-free strategies in this context.