Built two sites recently for my own business, one on flatsome theme, the other on porto. Both on the same server. The porto site is slow despite having no products loaded yet etc but the flatsome theme site is much faster. This made me go down the rabbit hole googling and seeing so many options and alternatives. I'm not very tech oriented so bricks/building my own is not an option (not sure I even understand fully what bricks is).

I've since seen flatsome suggested as reasonable, and also Astra and shoptimizer.

For reference we have around 5,000 products. We want medium to long term viability but are happy to change in years to come should we need increased performance etc.

It's hard for me to fully understand this and grasp everything, but essentially as we in the process of changing websites anyways (we previously used shopify), is it worth changing the porto theme site to something else before we put lots of effort in customising things? And if so what's the best option for someone who's happy to put in time and effort changing and customising things, but does need some vague templates and options that make things easier for me?