StreamWriter class - is it resource extensive?

I need to make some sort of an EventViewer class, which will append some events in a file. and when necessary display the events to user. There could be up to 300 events per day, but usually its around 100 events per day. What approach should I take in this situation? This is what I am thinking at the moment:

1) I could make EventViewer class declared as static, and have StreamWriter (used by EventViewer internally) open the file, and keep it open for the application lifetime.
2) I could make EventViewer class declared as static, and have StreamWriter (used by EventViewer internally) open the file whenever it needs to write an event, and close it after it is done


Which one would you choose, performance wise, or if you have some better opinion, I would be glad to hear it.

Thanks,
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