diff --git a/src/api/dart_ffi.rs b/src/api/dart_ffi.rs
index c51ae45..60a92d4 100644
--- a/src/api/dart_ffi.rs
+++ b/src/api/dart_ffi.rs
@@ -647,12 +647,12 @@ pub unsafe extern "C" fn derive_zip32(
 
 #[no_mangle]
 pub unsafe extern "C" fn get_downloaded_size() -> usize {
-    DOWNLOADED_BYTES.load(Ordering::SeqCst)
+    DOWNLOADED_BYTES.load(Ordering::Acquire)
 }
 
 #[no_mangle]
 pub unsafe extern "C" fn get_trial_decryptions_count() -> usize {
-    TRIAL_DECRYPTIONS.load(Ordering::SeqCst)
+    TRIAL_DECRYPTIONS.load(Ordering::Acquire)
 }
 
 #[no_mangle]
diff --git a/src/chain.rs b/src/chain.rs
index 3da6de6..7bf17a9 100644
--- a/src/chain.rs
+++ b/src/chain.rs
@@ -7,6 +7,8 @@ use crate::{advance_tree, has_cuda};
 use ff::PrimeField;
 use futures::{future, FutureExt};
 use log::info;
+use rand::prelude::SliceRandom;
+use rand::rngs::OsRng;
 use rayon::prelude::*;
 use std::collections::HashMap;
 use std::convert::TryInto;
@@ -166,15 +168,15 @@ pub async fn download_chain(
             hash: vec![],
         }),
     };
-    DOWNLOADED_BYTES.store(0, Ordering::SeqCst);
-    TRIAL_DECRYPTIONS.store(0, Ordering::SeqCst);
+    DOWNLOADED_BYTES.store(0, Ordering::Release);
+    TRIAL_DECRYPTIONS.store(0, Ordering::Release);
     let mut block_stream = client
         .get_block_range(Request::new(range))
         .await?
         .into_inner();
     while let Some(mut block) = block_stream.message().await? {
         let block_size = get_block_size(&block);
-        DOWNLOADED_BYTES.fetch_add(block_size, Ordering::SeqCst);
+        DOWNLOADED_BYTES.fetch_add(block_size, Ordering::Release);
         if cancel.load(Ordering::Acquire) {
             log::info!("Canceling download");
             break;
@@ -606,7 +608,8 @@ pub async fn get_best_server(servers: &[String]) -> Option<String> {
             tokio::spawn(timeout(Duration::from_secs(1), get_height(s.to_string()))).boxed();
         server_heights.push(server_height);
     }
-    let server_heights = future::try_join_all(server_heights).await.ok()?;
+    let mut server_heights = future::try_join_all(server_heights).await.ok()?;
+    server_heights.shuffle(&mut OsRng);
 
     server_heights
         .into_iter()
diff --git a/src/gpu.rs b/src/gpu.rs
index fc38645..a6ce1f0 100644
--- a/src/gpu.rs
+++ b/src/gpu.rs
@@ -125,7 +125,7 @@ fn collect_decrypted_notes(
             for (output_index, co) in tx.outputs.iter().enumerate() {
                 let plaintext = &output_buffer[i * buffer_stride + 64..i * buffer_stride + 116];
                 // version and amount must be in range - 21 million ZEC is less than 0x0008 0000 0000 0000
-                if plaintext[0] <= 2 || plaintext[18] <= 0x07 || plaintext[19] != 0 {
+                if plaintext[0] <= 2 && plaintext[18] < 0x08 && plaintext[19] == 0 {
                     if let Some((note, pa)) =
                         domain.parse_note_plaintext_without_memo_ivk(&ivk, plaintext)
                     {
diff --git a/src/scan.rs b/src/scan.rs
index f0d4527..195d9ff 100644
--- a/src/scan.rs
+++ b/src/scan.rs
@@ -140,7 +140,7 @@ pub async fn sync_async(
                     .iter()
                     .map(|db| db.count_outputs as usize)
                     .sum::<usize>();
-                TRIAL_DECRYPTIONS.fetch_add(n_ivks * outputs, AtomicOrdering::SeqCst);
+                TRIAL_DECRYPTIONS.fetch_add(n_ivks * outputs, AtomicOrdering::Release);
                 for b in dec_blocks.iter() {
                     let mut my_nfs: Vec<Nf> = vec![];
                     for nf in b.spends.iter() {