This is a subject that makes business possible or not in Russia. I have had the best luck with EMS being the fastest from the US, 11 days sending 25kg box delivered to my apartment on a Sunday morning. Still sealed and no delays in customs if sent and sealed by the post office in US. Flagged automatically if not.
FedEx and UPS both are expensive and longer because of a minimum 4 extra days in customs if all is in order. If coming from a business, customs is smooth usually but not if from an individual.

Mail is not bad within Russia or with a city particularly but much longer from or to the outside world. 6 weeks average.
My office has tried a few mailing services, The current one is the worst but by far the cheapest. We use Westpost now and have had more lost mail then ever, long delays between deliveries to us after being stamped in Finland having arrived there. Generally very unreliable so we use them less and less, only using it to deliver newspapers from Finland now. Even then, we won't get a daily Finnish newspaper until they stack up and they are delivered(most of them) to the office in a batch of 6-7 editions. We are paying for daily courier but obviously are not getting what we are paying for.
We used one that was excellent and SPb to NYC was typically 3-4 days from pickup at our office. Return was the same but the monthly subscription keep increasing in price when we really did not need daily service.

I have has shipments of vacuum tubes from China that have been a nightmare no matter how I do it, They are small lots of 1 cubic meter, sent post or EMS and each time, over a year we still have never been able to get a parcel out of the post office. The total cost of the items are in the $200 range, just tubes used on guitar amplifiers because none are sold here, despite two factories making them in Russia. I made the mistake the first time having them sent to my name, a foreigner, and after 3 months and 100 hours of traveling back and forth to the central post office, creating documents describing them in great detail they always wanted more, until they decided they wanted $560 in fees to allow me to get them. We had them sent back, they were sent back only after weekly bugging them for 3 months. Had them sent again but to a Russian citizen, my GF, and the problem there was when they arrived, the invoice name spelling was slightly misspelled by the Chinese company, a transposition of 2 letters and the whole process started over and we still do not have the tubes. We filed every document required, notarized translations from Mandarin, certifications from an electronics specialist that they were what they said the items were. Then they noticed that the invoice was value had changed, during the wait because of the change in exchange rate so the invoice no longer stated the correct value in the many months of trying to get them out of the central post office. Finally, the just stopped taking to us and said it was lost. So I am into it about $900 for a $200 order, over a year and still have nothing. Each time they are sent back I get charged another $100 for shipping the 3.5g package. I was cheaper to fly to California and buy some there, which I just did this week. The ironic thing is that I do not even have the amplifier the tubes were for anymore.

For regular imports I have registered a company to import and distribute a line of US made amplifiers. Using a friend's logistic's company and since the there are only 4 models and shipping from business to business, everything is much more organized. Yes, there are duties, customs brokerage fees, VAT and all but so far all is as predicted. So it matters how you send things and where.

I just sent a piece of electronic test equipment from myself to myself from California. Packing, fees(had it professionally packed), EMS and insurance was $365 for 16kg. It should be there 11 days after it is sent. I left instructions to not enter it into the system until yesterday so I would be be there to receive it. I will report when it arrives. It is a unit I have had for 20 years so its value is hard to guess.