It's hard to say exactly what your issues are but they are likely due to issues with themes and plug-ins. You may have a exploited site as well, running nasty things in the background which could kill your CPU resources.
You don't need a dedicated server but I would recommend a VPS for that set up. You will get better performance overall which will help boost your Google rankings which will boost your traffic which will boost your revenue.
We have a very nice SSD VPS available right now for $50 monthly. Feel free to email
[email protected] and we will get you rolling ASAP.
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