Is a store effect performance to other multistore in the same magento install?
e.g.) if A store have 40000 sku products, and B store(which in same magento install with A) have only 100 sku products, is B store become slow due to A's products number like search result?
What other thing is effected to each store?
If there is many products and each store have many language store view, is it recommend to create each separate store with different magento install?
Our client driving such platform. We have 70+ stores, each 10k-40k products on sale. I don't know about traffic, but system work pretty good for such load. We don't meet any system halts caused by traffic yet. Sacrifice of speed is noticeable, but not critical. We use Magento EE with SOLR and FPC.
Performance issues can be a result of many different things, but one thing i do know is that 40k products with custom options and multiple attributes shouldn't affect the performance that much if you are running 2 stores in the same instance.
Magento is built for multistore setups, however it wouldn't be a suitable platform if you were to add 50+ stores (You could possibly use Enterprise given the fact it has SOLR search and FPC native as well as background indexing). As more stores are added, the amount of data in cache will multiply. Magento will also create copies of the flat tables, increasing indexing time, among other things.
Server setup and performance would be the next thing to look at.
