High memory usage usually stems from storing large datasets or recursive calls. Optimize storage, and use iterative solutions when possible.

Excessive memory consumption in competitive programming can be due to storing large data structures, unnecessary variables, or deep recursion. To reduce memory usage, analyze if large arrays or vectors are necessary, and only store what's required for the solution. If recursion depth is high, consider converting to an iterative approach, as recursion can consume stack space quickly. In languages like Python or Java, garbage collection may handle memory more dynamically, but efficient use of data structures like hash maps or sparse matrices is still essential. Optimizing memory helps to avoid memory limit exceeded (MLE) errors, especially when working within strict competition constraints.