It undoubtedly will become a normal situation that the computer gets slower and slower if you keep downloading various files or programs without deleting. Surfing on the Internet makes the web browser get the chance to bring the computer with unnecessary files such as caches, temporary files...
Learn music with your inner heart, touch life, keep writing and keep modifying your songs.
When a song is finished, you can let others who can sing well to sing your songs and upload them to famous websites(professional and music related is better?you can try and try...)
Keep and learning...