**tl;dr**

There is no silver bullet solution. There are some workarounds, I suggest `Sonassi_Fastsearchindex` - but that's specifically for catalog search. 

Perhaps disabling index updates on save - scheduling to run overnight - will provide some relief?  Combined with adding more caching - memcached, Redis, APC - and a full-page-cache like Varnish (if you're running CE) may get you started. If you plan on using Varnish, look at `Nexcess_Turpentine` on github for a quick-start.

**More information**

The indexing issues - specifically catalog_url_rewrites - are well known and documented in the community. Magento has handled these in the Enterprise version because these are the customers who are most adversely affected. Many EE customers have 10k+ products and multiple store views, websites, etc. 

The questions to ask yourself:

- Am I losing business due to indexing issues?
- Am I losing *productivity* due to indexing issues?
- Am I at risk of losing conversions or is my conversion rate suffering?
- Are my customers at risk of purchasing items out of stock that are a direct result of indexes being out of sync (inventory, etc.)
- Are my catalog pricing rules part of my core business and 
- Is my on-site-search conversion rate higher than norm (8-10%), thus benefitting from better indexing?

There is no silver bullet solution to this particular issue - as a solution provider you should help your customer make the decision that will best improve sales and the business while keeping overhead costs low.

**Alternatives**

Scale horizontally. Add more Apache/nginx servers. More servers = more concurrent throughput. This isn't 1:1. Nexcess has a great whitepaper on performance and Apache configuration here: http://www.nexcess.net/magento-best-practices-whitepaper

And, if you opt to go with Varnish - remember:

![enter image description here][1]


  [1]: https://i.sstatic.net/8ZQrO.jpg