It is known that the Russian Post Service (Почта России) is notoriously unreliable and slow
Actually, that's no longer true. In November 2016 I've sent two heavy packages using the cheapest regular mail service from Czech Republic to a middle-sized city in Russia. The packages took 3 days to leave the Czech Republic and then took only 10 days to get delivered to the recipient. Here's the tracking screenshot so that you don't have to believe me.
So unless you need the package to be delivered urgently, simply mail them at the post office in your home country. They should arrive within 2-3 weeks at the latest.
If you explicitly don't trust the Russian Mail Service no matter what, you can try express shipment options. However, some companies like DHL Express do not ship express parcels to Russia since 2014 due to complications on the customs. Same for FedEx. This usually does not affect shipping of documents, which is still possible with DHL Express.
Among other express shipping companies, UPS may be a good choice, hopefully they still ship to Russia. Other products (EMS) are not significantly better than the regular postal service. There are also some cheap good options to send packages from Russia (e.g. Dimex), but they don't accept shipments in the other direction.