Priority fees and MEV on Solana, a practical guide

Two things every Solana trader eventually hits: transactions that vanish without executing, and fills that come in worse than quoted. Both trace back to the same mechanism.

Ordering. Who gets in, and in what sequence.

What a priority fee buys

Position in a queue.

Base transaction fees on Solana are tiny, around 0.000005 SOL, and they don't move with demand, so when more transactions arrive than a block can possibly hold, something has to break the tie between them, and the priority fee you attach is that something.

Higher fee, earlier consideration. Nothing else. It won't make your transaction more likely to succeed on price, and it protects you from nothing.

Why transactions disappear

The most confusing failure mode, because nothing appears to happen at all.

Your transaction has a limited lifetime tied to a recent blockhash. Submit it with no priority fee during a busy period and it may simply never get included, then expire silently. No error, no revert, no explorer entry showing a failure.

Traders usually interpret that as a wallet bug. It's congestion, and the fix is a fee that reflects current conditions. Solana RPC errors covers telling this apart from an actual failure.

Setting one sensibly

Three levels, and most wallets expose them.

Normal conditions. Default settings work. You're paying fractions of a cent and getting included in the next block or two.

Busy periods. Raise it. A visible launch or a market move produces a surge, and the difference between a fee that works and one that doesn't is still well under a cent.

Time-critical trades. Set it high deliberately. Missing a fill during a move costs far more than any fee has ever cost anyone.

Rule of thumb: retrying a failed swap 4 times costs more in wasted attempts and worse prices than setting the fee correctly the first time.

What MEV is

Value extracted by controlling transaction order.

If somebody can decide whether your trade goes before or after theirs, that position has monetary value, and capturing it is the entire business. On Solana this works through validator relationships and staked connections rather than through a public mempool.

The common form is the sandwich: a buy inserted before yours to push the price up, and a sell straight after to capture the difference. Sandwich attacks explained covers the shape in detail.

The connection between the two

Now the part that ties them together.

A high priority fee gets you included faster, which narrows the window in which somebody could position around you. Real effect, and a small one.

Slippage tolerance does far more work, because a sandwich can only ever take what your own setting permits, meaning a 3% tolerance caps the damage at 3% while a 30% tolerance hands over ten times as much room to work in. What is slippage covers the practical numbers.

So the useful priority order is: set slippage tight, set priority fee adequately, and stop worrying about the rest.

What creators should know

Two things that affect your launch directly.

Your buyers hit congestion at exactly the moments you most want them buying, since a coin getting attention is a coin generating load. What do they conclude when a swap silently disappears? Usually that your token is broken, and a few of them say so publicly.

And any automated activity on your coin faces the same conditions. A system that doesn't track confirmations and resubmit delivers a fraction of what it promised during busy periods, invisibly, unless you count the trades yourself. Solana volume bot vs Pump.fun volume bot covers asking about that before you buy anything.

Two settings that end most of this

Priority fees buy queue position and cost almost nothing, so set them adequately rather than minimally. MEV is value taken from transaction ordering, and your slippage setting decides how much of it anybody can take from you. Tight slippage, adequate fee, and most of these problems stop happening.