Code Optimization Questions

Does performance and optimization make a difference? I have some questions about AI and would like to discuss them with professionals in the field.

• Reduce exceptions using return patterns in high-level layers. Exceptions should occur only in low-level layers.
• Prefer primitive types in request and response models. Avoid sending complex objects. For example, use string[] instead of List<string>.
• Guard Clauses are a useful technique.
• Reuse buffers and objects when possible. Avoid creating temporary objects in critical loops. Use Span<T> or Memory<T> for operations with large strings and arrays.
• Keep conditions simple and clear. Prefer lookup tables or dictionaries instead of multiple if/else statements to map values.
• In heavy loops, use simple for loops instead of foreach with arrays. Avoid loading everything into memory unnecessarily.

Just as there is optimization and performance considerations on the database side, regarding queries, I would like to understand the coding side as well.

I have one year of experience as a developer. Is it necessary to write optimized code in everything? I want to understand better to avoid over-optimizing, reducing allocation to the minimum, and becoming fanatical.